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Marine Fishes
Marine fishes are an eclectically diverse group of vertebrates that dwell in saltwater environments such as seas and oceans. They are adapted to dwell in different types of aquatic habitats, from rocky shores and coral reefs to deep-sea trenches and open water. Here are some exciting facts about marine fishes as a group:
Diversity – Marine fishes are very diverse, with over 30,000 identified species. They exhibit an astounding array of shapes, sizes, colours, and behaviours.
Adaptations for life in water – Marine fishes are enabled to thrive in their aquatic environment courtesy numerous adaptations. These adaptations include gills for extracting oxygen from water, the ability to regulate their buoyancy utilising swim bladders or other mechanisms, and streamlined bodies for proficient swimming.
Coloration – Various marine fishes exhibit vibrant colours and patterns, which serve different purposes. Coloration is used by some marine fishes for camouflage to make blending with their surroundings possible, while others use bright colours to warn predators of their toxicity or attract mates.
Migration – Quite a few marine fish species carry out long-distance migrations for fulfilment of their life cycle requirements. For instance, salmon migrate from the ocean to freshwater rivers to spawn, whereas few species of tuna carry out extensive transoceanic migrations.
Symbiotic Relationships – Marine fishes very often engage in interesting symbiotic relationships. One great example is the relationship between cleaner fish and larger predatory fish. The cleaner fish feed on parasites and dead skin off the larger fish, providing an exceptional cleaning service in return for guarantee of protection.
Electric Abilities – Some marine fishes have the ability to generate electric fields. Electric eels and electric rays are capable of producing electrical shocks to stun prey, navigate, and communicate.
Reproductive Strategies – Marine fishes demonstrate a variety of reproductive strategies. Some give birth to live young ones while others lay eggs that are fertilized externally. Some species even undergo sex change, they start their life as one sex and end their life as other.
Longevity – Some marine fish species have unusually long lifespans. For example, the Greenland shark is known to have several centuries long lifespan, easily making it one of the longest-lived vertebrates in the world.
Threats and Conservation – Marine fishes face innumerable threats, including habitat destruction, pollution, overfishing, and climate change. Conservation efforts are vital for protecting these species and maintaining the well-being of marine ecosystems.
Economic Importance – Marine fishes play an important role in human economies across the world. They are a vital food source, support fishing industries, and promote tourism through activities like scuba diving and recreational fishing.
These are very few of the many curiosity arousing facts about marine fishes as a group. Their adaptations, diversity, and ecological worth make them a fascinating subject of study.
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6 Types of Lions around the World
If you are animal lover you will love this fact-based article on the most regal animal in the world, the Lion. The lion is easily one of the most iconic animals on the earth. With its imposing presence and striking mane, it is absolutely unsurprising this big cat is so revered. Lions are found in Asia and Africa. In Asia, lions inhabit grasslands and semi-arid areas. In Africa, they can be sighted in a variety of habitats, from dense forests to open savannah. Lions are social animals and like to stay in groups called pride. A pride normally consists of around 20 lions but can have as many as 40. Only males have mane, and mane grows thicker as they age.
Lions are natural predators and consume a variety of prey, including antelope, buffaloes, zebras, and wildebeests. Lions can run fast up to 50 miles per hour and can leap up to a height of 18 feet. Despite being one of the most loved animals in the world, lions are facing an existential threat. They are listed as vulnerable by the International Union for Conservation of Nature (IUCN). Poaching and habitat loss are the main threats to lions.
Introduction to the Most Regal Animal in the World, the Lion
When people find out that there are diverse breeds of lions they get curious to know how many types of lions still remain in the wild and how many are surviving in captivity. There are eight different types of lions. We will talk about six types of lions in this article. Many people are unaware that the lion is an endangered animal.
Different Types of Lions
There are several similarities in all types of lions. All breeds of lions live in a pride, they are all very close-knit and warm towards one another, they all nurture their cubs in the same manner and the lionesses of all species are the hunters. The variances come in the development of the fur and the colour of the fur. The height, weight, colour, length, and fur type may differ a bit from species to species.
Asiatic lion
The scientific name of Asiatic Lion is Panthera Leo Persica. This animal quite naturally is a meat eater that lives at least to the age of 16 or sometimes even more. Size of this majestic animal is akin to a six-foot man and it reaches 300 to 500 pounds.
The African Lion and Lioness
The African Lion is regarded as the second largest lion in the world. The male lion has a remarkable, long, bushy mane of hair covering the head and the neck. This bushy hair acts as protective gear for the head and the neck. When the males indulge in fight this bushy mane serves as protection to the head and the neck.
Katanga Lion (Southwest African Lion)
These lions are labelled as truly the Kings of the Jungle. This lion lives in family units or prides and works really hard to protect its family’s pride. They have a characteristic mane of hair around the head and the neck. Hunting is the responsibility of the lioness of the family. When the cubs afre one year old they are taught to hunt.
White lion
The story of these regal creatures is a gloomy story to those who love these animals. Hearts go out to each and every White Lion who can no longer be free to roam or at least be safe in a secure natural environment. White lions in the wild are searched for with the primary aim of protecting and safeguarding these types of lions.
Masai lion
These kinds of lions have been described as having comparatively longer legs and their bodies are comparatively less stocky or plump. Their backs do not look as curved as other lion species. The males have tufts of fur on their knees. The males possess manes but they are not very thick and look like they are backward combed. The Masai lion also known as Panthera leo nubica or the East African lion is a lion species found in eastern Africa or Nubia.
The Abyssinian
Science is working very hard to find the answers to DNA of this lion type, they are a mystery to science till now. In 2012, scientists learnt that this lion species may be the last of a sub-species of a lion called the Abyssinian lion. These lions are smaller and possess considerably longer manes that continue under the torso and along the belly. DNA samples of this breed were examined, and it was learnt that no other lion species have the same DNA.
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Some animals are moving towards a certain extinction. A new habitat might be their last chance
Some of the most endangered animals might not be able to survive in their current habitat because of climate change. Researchers are pondering on a controversial strategy to relocate them before it’s too late — beginning with Australia’s rarest reptile.
A lone radio tower in a remote national park of Australia stands above a quiet wetland. It collects signals every five seconds from a few dozen young tortoises hiding out beneath the glassy waters. The tiny tortoises don’t travel far, but researchers are meticulously tracking their every move. The fate of this species (one of the most endangered in the world) might be dependent on these data. In August last year, scientists chose 41 adolescent tortoises from a captive-breeding programme in a zoo and released them into this national park on Australia’s most southwestern tip, some 330 kilometres south of natural habitat of the tortoises. The goal is to observe whether the animals can tolerate cooler climates, and whether this new habitat is fit enough to secure the species’ future as the planet warms. This experimentation is part of a series of meticulously monitored field trials testing one of the most contentious strategies for saving a species — a concept termed assisted migration.
This project attempting to save the tortoise is led by a herpetologist at the University of Western Australia in Perth, Nicki Mitchell. “It is a demonstration project for the world, and we particularly want to make sure there are no perverse outcomes,” Mitchell says. Her team is now conducting their fourth trial of releasing captive-bred tortoises into chosen wetlands to assess the potential of assisted migration or assisted colonization.
Assisted migration has faced stiff resistance from conservation biologists and land managers mainly because of the threat that introduced species may become invasive pests, carry diseases or upset existing ecosystems. Few places have faced such risks more than Australia, which has fought against rabbits, cane toads and other invasive species that people purposefully introduced to the continent under disastrous schemes. But opinions about assisted migration are gradually changing as conservationists feel compelled to rethink as the have realised just how fast the climate is changing. Several other projects are in the works apart from swamp tortoise experiments. Researchers in Hawaii are relocating seabirds to higher ground while in eastern Australia scientists are testing plans to move critically endangered pygmy possums. Increasing temperatures and droughts have become a threat for pygmy possums while seabirds need to be protected from rising seas that are destroying their nesting habitat rapidly.
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20 Types of Edible Fish
Have you been just consuming only one kind of fish because that’s the only one you know? For you, it might be the best one most probably because you haven’t tried other options and you are just not aware of their taste. It is a distinct possibility that you didn’t even know that over 40 different kinds of edible fishes exist. You may have seen some mentioned on a restaurant’s menu but failed to take notice.
Sticking to one option is not a bad idea at all but you might be missing out on a lot of scrumptious food and nutrition. Who likes that? Do you want to explore the wide variety of edible fish but don’t know where to begin? Rely on us. We have resorted to deep search to make a list of top edible fishes that don’t only boast of good looks but taste delicious too.
Before diving into the deep sea to catch the fish let’s just first enhance our awareness about the types of edible fish.
Types of Edible Fish
There are two types of edible fish:
White edible fish
Blue edible fish
White Edible Fish
Occupying the sea bed, this type consists of a huge number of species. Low in fat content they make them easily digestible. A white fish mandatorily has a straight tail edge. This is a way to recognise white fish while making a purchase in a store.
Blue Edible Fish
These are fishes that keep migrating and have a high-fat content in their meat. Due to high fat content blue edible fish are very difficult to digest and can cause obesity. The blue edible fish are recognisable by an arrow-shaped tail.
20 Types of Edible Fish
Now let’s take a look at different edible fish you can have but might be missing out on. They are delectable and taste differently.
Branzino
Branzino also known as European sea bass is a silver-skinned tender fish. It can be caught in the native Mediterranean Sea, in the Black Sea and the eastern Atlantic Ocean from Norway to Senegal. It is known for its mild and slightly sweet taste. It is usually eaten in roasted form and is served with lemon in restaurants. Pregnant women, children under six should and or those who are planning to have a child should avoid eating it. Tuna can be an alternative.
Tilapia
Just like Branzino it has a mild and sweet taste. It is a great source of protein. Pasta and salad are great accompaniment with Tilapia. Different recipes are available to cook it at home itself. Health experts advice avoidance of tilapia since it contains a high amount of omega-6 fatty acids known to cause inflammation.
Codfish
This saltwater fish and can be caught in the Pacific, New England, and the Atlantic. It is generally served without the head since many people find it undesirable. The taste varies from region to region. Pacific Cod is savory whereas Atlantic Cod is sweet and soft. It is advisable to get a fresh cod because a frozen one doesn’t taste good. Over-consumption should be avoided as mercury content can damage the brain.
Hake
It can be caught in Southwest Pacific, the Southwest Atlantic, Southeast Atlantic, Southeast Pacific, the Mediterranean, and the Black Sea. They are similar in taste to Atlantic Cod. They generally have slightly sweet meat, have a soft texture and taste mild. These are inexpensive and alternate for cod.
Sea Bream
Edible sea breams can be caught in the eastern coastal regions of the North Atlantic Ocean and the Mediterranean Sea. Mediterranean is the best sea bream species. The best sea bream species is the Mediterranean, also called Golden-headed Bream. Perfect seasoning and roasting is necessary for achievement of best taste. It is very expensive due to high demand.
Salmon
It is a famed fish known across the world. They are prevalent in the streams leading to the Pacific and Atlantic oceans. Restaurants usually prefer the Atlantic one. It has a refreshing and mild taste to it. Taste is dependent heavily on the high-fat content of the fish. Various types of salmon like red salmon, chum salmon and pink salmon are available. Pregnant women should not consume salmon.
Mackerel
They are prevalent in the temperate and tropical seas. It has a sweet taste and tastes similar to tuna. It’s advisable to buy it fresh to avoid the fishy taste of it. Grilling is the best way to cook it. You can enjoy it with pasta or a sandwich. 305 calories is contained in 100 grams of Mackerel.
Brill
This shallow water fish is found in southern Iceland, the Mediterranean, Western Europe and the Black Sea. It’s very meaty and slightly sweet. It tastes like Turbot. Skin is rough and tastes bitter so it’s better to avoid the skin. It is commonly served with butter and herbs. Brill is outstanding for grilling or pan-frying.
Sea Bass
The Chilean Sea bass is prevalent around Antarctica and in the Southern Ocean. Sea bass tastes like cod and is mild and slightly sweet. It is moist and tender. Black sea bass, rock sea bass, and striped sea bass are various types of sea bass. Expensive cooking makes it a restaurant variety.
Yellowtail
It can be caught in the western Atlantic Ocean that includes the Caribbean Sea and the Gulf of Mexico. It is sweet and mild in taste with a buttery texture. Cooked Yellowtail is white fleshed and tastes outstanding. Yellowtail can be effortlessly baked and cooked like tuna.
Tuna
They are prevalent in most of the oceans of the world. It is one of the most costly fish in the market and has a delicate taste to it. Raw tuna is quite mild and tender and possesses an oily texture. Tuna steaks have a meaty texture and sweet taste. It is best enjoyed with brown rice.
Trout
They are prevalent in lakes and streams. There are various types of trout like brown trout, rainbow trout and sea trout. All of them have different flavour. Rainbow trout has a delicate texture and fish flavour. You can use pickled mango and roasted root vegetables as accompaniment with trout.
Pollock
This marine fish prevalent in the Atlantic Ocean is renowned as Gadus Pollachius. It has quite a mild, delicate taste with a very coarse texture. They taste like cod but are less costly. It is best accompanied with salad and beans.
Haddock
This saltwater fish is well-known as Merlangius Aeglefinus. The fish can be caught in the Atlantic Ocean, the North Sea and seas off Iceland. It has an oily and flaky texture and a mild flavor to it. You can enjoy it with crushed garlic and avocado cubes. Haddock can be quickly cooked in about 20-30 minutes.
Turbot
They are prevalent in shallow waters throughout the Mediterranean and Norwegian sea. They were earlier known as Psetta maxima. Their great flavor is one of the reasons for their expensiveness. These can be easily cooked at home.
Sardines
Part of the family Clupeidae, these are small oily fish. Mediterranean island of Sardinia is where this fish is most abundant, hence the naming. The taste of the sardines hinge heavily on how they are cooked. Tinned sardines are far less salty. They possess a rich taste and the flesh is very meaty. You can enjoy fried sardines or have them on toast. They can become part of salad as well.
Red Mullet
They are very popular in Mediterranean cuisine and are renowned as Mullus Bhavearbatus. It is a goatfish species. It is found across the Mediterranean and the Black Sea and has a strong taste. They are small compared to other fish though. The fish can be cooked whole or in filleted form. Avoid it from May to July. August to October is the best time to eat them.
Perch
Yellow perch is an edible perch. Found in drainages of Arctic and Atlantic oceans and also in the Mississippi River, it’s one among the scrumptious freshwater fish in America. They possess a flaky white flesh and have a mild sweet taste. Can be deep-fried, panned, baked, and cooked with mild seasoning.
Walleye
Also known as yellow pike or yellow pickerel, Walleye is native to Canada and Northern United States. This freshwater fish has a sweet flavor and its firm texture gives your mouth a buttery feel. Grilled vegetables, pasta, potatoes, and salad are great accompaniment of walleye. This fish is low on fat.
Catfish
Catfish taste great although they don’t look particularly tempting. The farmed variety of catfish have a mild, sweet taste. They are not at all flaky and have moist flesh. Potato salad, cornbread, red beans, and rice, and macaroni and cheese are great accompaniment of catfish. It is low on calorie and high on protein.
Conclusion
Now you have become aware of some of the most famous edible fish. Each of them tastes great in its distinct way if cooked well. Remember, this list is definitely not all inclusive and there are many more fish you can try.
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Mammoth Mission: How Colossal Biosciences Intends to ‘De-Extinct’ the Woolly Mammoth
Ten thousand years after the last woolly mammoths died out along with the last Ice Age, a team of computational biologists is in mission mode to bring them back within five years (by 2027). Led by synthetic biology pioneer George Church, Colossal Biosciences is out to de-extinct the dodo bird and Tasmanian tiger, and help save current-day endangered species as well.
“The woolly mammoth is a very iconic species to bring back,” said Eriona Hysolli, head of biological sciences at Austin, Texas based Colossal Biosciences. “In addition, we see that pipeline as a proxy for conservation, given that elephants are endangered and much of this work directly benefits them.”
Plenty of work needs to be done on endangered species. According to Colossal, critically endangered African forest elephant has declined by nearly 90% in the past three decades. Between 2010 and 2012 alone, poaching took more than 100,000 African elephants, according to the company. “We might lose these elephant species in our lifetime if their numbers continue to dwindle,” said Hysolli.
Humans triggered the extinction of many species, computational biologists are now attempting to bring them back with CRISPR and other gene-editing technologies, advancement in AI, and bioinformatics tools and technology, like the NVIDIA Parabricks software suite for genomic analysis.
To bring back a woolly mammoth, scientists at Colossal began with mammoth and elephant genome sequencing to identify what makes them similar and different. Next steps include using Asian elephant cells to engineer mammoth changes responsible for cold adaptation traits, shifting the nuclei of edited cells into elephant enucleated eggs before instilling them into a healthy Asian elephant surrogate.
Tech Advances Drive Genomics Leaps
It took colossal effort over two decades, not to mention $3 billion in funding, to first sequence the human genome. But that’s now been reduced to matter of hours and under $200 per whole genome, by virtue of the transformative impact of AI and accelerated computing. Colossal co-founder Church is well aware of this. “There’s been about a 20 millionfold reduction in price, and a similar improvement in quality in a little over a decade, or a decade and a half,” Church said in a interview on the TWiT podcast.
Research to Complete Reference Genome Puzzle
Colossal’s effort to build a reference genome of the woolly mammoth is akin to trying to complete a puzzle. DNA sequences from bone samples are assembled in silico. But degradation of the DNA over time often doesn’t leave all the pieces intact. The gaps to be filled can be guided by the genome from an Asian elephant, the closest living mammoth relative.
Analysis Targeting Cold Tolerance for Woolly Mammoth
A lot is at stake in the sequencing and analysis. The Form Bio platform boasts of tools that can assess whether researchers make the right CRISPR edits. “Can we identify what are the targets that we need to actually go after and edit and engineer? The answer is absolutely yes, and we’ve gotten very good at selecting impactful genetic differences,” said Hysolli.
Scientists have collected multiple specimens of woolly mammoths over the years, and the best are bone or tooth samples found in permafrost. “We benefit from the fact that woolly mammoths were well-preserved because they lived in an Arctic environment,” said Hysolli. According to Ben Lamm, Colossal CEO and co-founder, an Asian elephant is 99.6% akin to a mammoth genetically. “We’re just targeting about 65 genes that represent the cold tolerance, the core phenotypes that we’re looking for,” he said recently.
Benefits to Biodiversity, Conservation and Humanity
“As we lose biodiversity, it’s important to bring back or restore species and their ecosystems, which in turn positively impacts ecology and supports conservation,” said Hysolli. Researchers need to realise how similar and dissimilar these animals are to each other so that in the future they can produce thriving populations, she said. It’s been discovered that elephants are far more resistant to cancer when compared to humans. Researchers are looking at the genetic factors leading to this and ways in which this could be replicated in humans. “This work does not only benefit Colossal’s de-extinction efforts and conservation, but these technologies we build can be applied to bettering human health and treating diseases,” said Hysolli.
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Recreating Extinct Animals or De-extinction: Facts and Concerns
De-extinction: A Fascinating Idea
Recreating an extinct animal species is a tantalizing idea for many people. Though there are problems still to be solved, the process is becoming feasible gradually. A few years ago scientists believed that recreating extinct animals was an impossible task, some have now started believing that it may be very much within the realm of possibility in the not-too-distant future, at least for few species. In fact, some Japanese scientists forecast that they will be able to clone a woolly mammoth in less than half a decade.
How is resurrection of an extinct species that has long disappeared from the earth even possible? Finding the DNA (deoxyribonucleic acid) of the species is the key. Genetic code of an organism is contained in this very molecule DNA. The genetic code is the set of instructions for building the animal’s body.
Once a sample of an extinct animal’s DNA has been isolated, the next step in the resurrection process is to zero in on an existing animal that has some similarities to the extinct species. For example, it is believed that elephant can play a role in resurrection of the Mammoth. The extinct animal’s DNA is inserted into an egg of the existing animal replacing the egg’s own DNA. The embryo that develops from the egg is then placed in a surrogate mother to develop.
Some Concerns About De-extinction
De-extinction is a topic highly fascinating but very controversial, with arguments galore both in support of the idea and against it.
Some concerns about resurrecting extinct animals include the following:
An organism is much more than just its genetic code. Events and experiences owing to its interaction with its environment affect its behaviour (and sometimes even its genes). Extinct animals if resurrected today would lack their original environment, so would they really be the original animal?
There are also apprehensions about how the recreated animals will impact ecosystems. Will they harm the environment or eradicate other species? Will they be destined to a life of captivity? Will their presence be unfavourable to humans?
Some people feel that the money splurged on cloning experiments should be spent to help solve social problems in human societies and to help people in distress.
The ethics of cloning bothers some. They regard genetic manipulation as a way of “playing God” and believe that humans have no right to do this.
Others are fearful that cloning may be dangerous because we are not well aware of the consequences of manipulating DNA.
The fact that multiple attempts at cloning are generally required in order to get success also upsets people. Many eggs and embryos perish in the quest to create a cloned animal.
Effect of the embryo of an extinct animal on a surrogate mother worries some sensitive people. For example, forcing a modern elephant to produce a mammoth baby or a hybrid elephant-mammoth is cruel in the eyes of some.
There is another lacunae with the idea of de-extinction that bothers some people. Many existing animals are at the verge of extinction, some researchers feel that it’s far more prudent to work on preventing new extinctions than to resurrect extinct animals from the past.
Some Possible Benefits of De-extinction
The key factor that spurs many researchers on is the pure wonder of de-extinction. It would be awe-inspiring to discover the true appearance of an animal that we know from only a few bones and to observe the animal’s behaviour.
Scientists may be able to spark the interest of public in animals still existing on the earth by sparking the public’s interest in extinct animals.
Many recent animal extinctions are resultant of human activities, such as hunting and habitat destruction. Some people feel that bringing back a species that we destroyed will be poetic justice.
Study and practice of cloning and genetic manipulation to create extinct animals is leading scientists to discovery of important information about DNA and genes and to learn new skills and techniques. Their knowledge may prove to be useful in the study of human and animal biology affecting our lives directly. It may even aid scientists in prevention and treatment of diseases.
Resurrecting specific animals may be beneficial in certain ecosystems.
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Medical devices take design tips from the animal kingdom
Millions of years of biological evolution has aided the animal kingdom to adapt processes and characteristics to meet specific needs. Using bioinspiration approach, scientists and engineers are employing insights from biology to solve today’s technological challenges and optimize the design of new materials, devices and structures. For example, researchers have designed a surgical imaging system based on the amazing eyes of the mantis shrimp in the medical field. Just last month saw the publication of two new research studies exploiting insights from biology for the benefit of human health.
Powered by pangolin scales
First up, the pangolin – the solitary mammal that’s entirely covered in hard scales. Rather than to each other, these scales connect to the underlying skin, and overlap in the style of a pine cone, allowing the pangolin to curl into a ball when threatened. It is these scales that provided the inspiration for designing a miniature soft medical robot to Metin Sitti from the Max Planck Institute for Intelligent Systems and his collaborators.
Untethered magnetic soft robots have the potential to accomplish minimally invasive medical procedures inside the body. In future, guided by magnetic fields such robots could be sent to hard-to-reach regions where they can then deliver drugs or create heat. Localized heating can stop bleeding, cut tissue or even ablate tumours. Remote generation of heat, nonetheless, requires the use of rigid metallic materials, which can compromise the compliance and safety of soft robots.
“To address this inherent trade-off between effective remote heating at long distances and compliance, we observed how pangolins in nature could still achieve flexible and unencumbered motion despite having keratin scales which are orders of magnitudes harder and stiffer than the underlying tissue layers, simply by organising the keratin scales into an overlapping structure,” write the researchers, in Nature Communications.
With this in mind, Sitti and colleagues designed and fabricated a 20 x 10 x 0.2 mm robot containing a soft polymer layer and a pangolin-inspired layer of overlapping metal elements. When researchers exposed robot to a high-frequency magnetic field, the robot delivered on-demand heating (by over 70°C) at large distances (more than 5 cm) within less than 30 s. By exposing it to a low-frequency magnetic field, the researchers could make it roll up and move about.
Emulating the octopus bite
“The predatory behaviour of the blue-ringed octopus inspired us with a strategy to improve topical medication,” writes a research team headed up at Zhejiang University and Sichuan University in China. In intratissue tropical medication, challenges like adhering drug carriers to soft tissue surfaces wetted by bodily fluids and controlling the concentration of drug release is faced. To overcome these impediments, first author Zhou Zhu and colleagues created a microneedle patch that facilitates robust tissue surface adhesion and active-injection drug delivery. Writing in Science Advances, they state that the drug-releasing microneedles work in a manner “inspired by the teeth and venom secretion of the blue-ringed octopus”.
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Great white sharks: largest predatory fish in the world
Great white sharks (Carcharodon carcharias), usually called white sharks, are regarded as the largest predatory fish in the world. This fact has been recorded in Guinness book of world records. Belonging to a partially “warm-blooded” family of sharks called Lamnidae, they are able to maintain an internal body temperature that’s warmer than their external environment. This is unlike other “cold-blooded” sharks.
Great white sharks are the only existing members of the genus Carcharodon. Greek words “karcharos,” which means sharpen, and “odous,” which means teeth, combinedly inspired the naming of genus Carcharodon. This name is most appropriate, as great white sharks have rows of up to 300 serrated, triangular teeth. These grey skinned white bellied sharks have bullet-shaped bodies.
Thanks to movies like “Jaws” (1975), great white sharks are one of the best-known shark species but in reality they live a very secretive lifestyle, and scientists still have much knowledge to gather about these iconic predators.
How big are great white sharks?
Great white shark size varies quite a bit. Females grow lengthier compared to males. Males manage to reach just 11 to 13 feet (3.4 to 4 m) while female great white sharks reach lengths of up to 15 to 16 feet (4.6 to 4.9 meters, according to the Smithsonian National Museum of Natural History in Washington D.C. Above mentioned figures are averages and the largest great white sharks can grow to 20 feet long (6.1 m). According to the Florida Museum of Natural History, there are unsubstantiated reports of great whites growing to 23 feet long (7 m). According to the World Wildlife Fund (WWF), adults weigh in the rage of 4,000 and 7,000 pounds (1,800 and 3,000 kilograms).
They may be largest predatory fish but great whites are not the biggest sharks in the world. That title is in safe custody of whale sharks (Rhincodon typus), which are filter-feeders and generally grow up to 33 feet (10 m) long and weigh around 42,000 pounds (19,000 kg). Point to be noted here is that now-extinct megalodon (Carcharocles megalodon) was the biggest shark species ever, which may have grown up to 60 feet long (18 m) or more, although its exact size is still being debated among scientists.
Where do great white sharks live?
Great white sharks have a wide habitation range; they inhabit most temperate and tropical oceans around the world and have resident populations off the coasts of the U.S., South Africa, Australia and other countries. They are usually sighted in cooler, temperate waters. According to the International Union for Conservation of Nature (IUCN), white sharks swim at the surface as well as deep down more than 3,900 feet (1,200 m) below the surface.
Great white sharks are known to be migratory and undertake long-distance journeys across the open ocean, perhaps for food and breeding. Researchers once tracked a great white shark swimming 6900 miles from South Africa to Australia before heading back.
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Ancient fires drove large mammals extinct, a new study suggests
Wildfires spurred by human activity caused disappearance of sabertooth cats, dire wolves and other large North American mammals, suggest fossils from La Brea Tar Pits in Southern California.
Wildfires are getting harsher. Frequency of wildfires has gone up three times compared to 20 years ago in some parts of United States, say scientists. Scientists also say that expanse of such wildfires is up to four times compared to wildfires experienced 20 years ago. Smoke from Canadian blazes this summer turned North American skies an unearthly orange. “Fire whirls” were sighted in the Mojave Desert and raging flames proved disastrous for Maui.
Studying records of the distant past lead us to reasons that drove increased fire activity in bygone ages and results of such increased fire activity. In a fresh study published on 16th august 2023 in the journal Science, a group of palaeontologists that examined and analysed fossil records at La Brea Tar Pits, a famous Southern California excavation site, drew conclusion that dire wolves, sabertooth cats and other large mammals in this region disappeared nearly 13,000 years ago due to rising temperatures and increased fire activity spurred by people.
“We implicate humans as being the primary cause of the tipping point,” said a Marshall University evolutionary biologist Robin O’Keefe. O’Keefe added, “What happened in La Brea, is it happening now? Well, that’s a really good question — and I think we should figure it out.”
Earth has gone through five mass extinction events so far; some scientists claim that the disappearance of large mammals at the end of the last ice age was the beginning of a sixth. “It was the biggest extinction event since an asteroid slammed into Earth and wiped out all the dinosaurs,” opined a paleoecologist at La Brea Tar Pits and Museum and author of the new study, Emily Lindsey. Emily’s opinion is that the said disappearance was “the first pulse” of sixth mass extinction.
As yet, researchers have been unable to pin down exactly what caused these animals to go extinct. La Brea Tar Pits is one of the very few sites on the earth with fossil record large enough for scientists to investigate the question. Still active pits spread across 13 acres of land, are covered with bubbling black asphalt that has seeped to the surface from inside Earth. Prehistoric animals that got stuck in this goo died due to fatigue or predation, and their remains got preserved and fossilized by the asphalt. “And that’s still happening today,” Dr. O’Keefe informed. “You can go out to La Brea and see a squirrel stuck in the tar — I’ve seen it with my own eyes.” That’s hard luck for the animals, but good fortune for scientists: La Brea now boasts of a continuous unbroken fossil record of the region stretching as far back as 55,000 years.
Dr. O’Keefe and his team studied fossils for eight large mammal species — including the sabertooth cat, Camelops hesternus, an ancient camel and the American lion — that lived between 10,000 and 15,600 years ago. The team found out that seven of these species went extinct around 13,000 years ago, relying on radiocarbon dating. To understand why, the researchers analysed climate, pollen and fire records in the region in conjunction with continental human population growth at the time. They discovered that human occupation began to rise briskly around the same time that Southern California entered a period of severe drought and warming. Extreme fires followed, and the vegetation, once rich in oak and juniper trees, was ultimately replaced by grass and chaparral shrubs. “What we see is that you have a 400-year-long period of massively elevated wildfire,” said a paleobotanist at La Brea Tar Pits and Museum and an author of the new paper, Regan Dunn. Regan added, “And at the end of that period, you’re in a different ecosystem and all of the megafauna are gone.”
Dr. O’Keefe termed the conditions as the perfect storm: “You have a bunch of different factors that are multiplying each other and giving you a huge increase in fires,” he said. Using a model akin to the ones that forecast movements in the stock market, the scientists concluded that humans were the principal drivers of these fires, both through direct ignition and by the elimination of herbivores (elimination of herbivores allowed flammable underbrush to spread uncontained). Shifts in the climate aggravated this further, setting the stage for the extinction of species.
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Invertebrates – Evolution and Classification
As the name suggests, invertebrates lack vertebral column, also known as spine or backbone. Insects, earthworms, spiders, octopuses, leeches, prawns, snails, oysters, squids and jellyfish are all examples of invertebrates. 97 percent of all animals found on earth are invertebrates.
Evolution of invertebrates
Charles Darwin propounded the theory of evolution by natural selection in 1859. In his book ‘The origin of species’ Darwin described how creatures evolve over generations through inheritance of behavioural and physical traits. According to the theory individuals with more adaptive traits will have better chance of survival and have more offspring compared to individuals with less adaptive traits. Over time descendants of individuals with more adaptive traits will become more prevalent in the population because of the adaptive traits they have inherited from their adaptive ancestors and thus evolution through natural selection happens. Whole lot of traits contribute in the evolution of invertebrates. The characteristics are multicellularity, cephalization, tissues and organs, mesoderm, complete digestive system, coelom, radial and bilateral symmetry, a segmented body, and notochord. Symmetry, cephalization and specialization are three key traits in invertebrates’ evolution. Let’s take a look at each of these traits to understand how invertebrates developed over time to become the wonderful animals they are today.
- Symmetry: Most but not all invertebrates possess bilateral symmetry (two halves almost absolute mirror images of each other), some have radial symmetry (all sides are the same). The symmetry that ‘radiates’ from the center is radial symmetry, symmetry of slices of pizza is example of such symmetry. Such symmetry is seen in sea anemones and sea stars. There are invertebrates that lack any symmetry, for example sponges.
- Tissue specialization: Essentially, as animals evolve and get larger and more complex, their tissues gain specialization in producing various body parts. Muscle cells differ from nerve cells as they have to perform specialized jobs different from each other. In the same way kidney cells differ from lung cells.
- Cephalization: Cephalization is nothing but development of an organism’s front end into a distinct head. Some creatures display complete cephalization, yet since their bodies are not divided into distinct trunks and heads, they cannot possess a distinct physical head.
Invertebrate classification
The evolution of invertebrates has caused diversification. There are over 30 phyla of invertebrates. Except for one, invertebrates compose the entirety of the animal phyla. Of the three subphyla of Chordata two are invertebrate-dominated and the third subphylum is Vertebrata. Vertebrata includes all vertebrate organisms. Fossil record provides confirmation to the well accepted fact that many invertebrate species have been extinct. The major classification of invertebrates that have avoided extinction are as follows:
- Porifera: Key members of the Porifera phylum are sponges. These earliest invertebrates are lowest multicellular animals. Sponges lack real tissues and have specialized cells instead.
- Cnidaria: Cnidaria are radially symmetrical and possess actual tissues. Jellyfish, hydrozoans and corals are included in Cnidaria. Many cnidarian species play a key role in the enormous coral reefs existing in tropical waters.
- Platyhelminthes: Flatworms are the most eminent members of the phylum Platyhelminthes. They possess bilateral symmetry and are formed from three germ layers of embryonic cells.
- Nematoda: Roundworms and flatworms are amongst the parasitic species found in the phylum Nematoda. Some of these are infectious to humans or livestock. Unlike flatworms, roundworms possess a complete digestive tract and a partly filled body cavity.
- Annelida: Annelida is a collection of segmented worms that includes ordinary earthworms and leeches. They possess a specialized digestive system, a primitive brain system and a closed circulatory system. Annelids possess a very well-developed body cavity, excretory system, nervous system and a rudimentary brain.
- Arthropoda: Arthropoda encompasses about 80% of all living species in the world. They possess segmented bodies with jointed limbs and an open circulatory system with multiple hearts. They possess a thick exoskeleton made of chitin (a complex polymer). They have an excretory system, a nervous system and a primitive brain.
- Mollusca: Mollusca phylum is of clams, squids and octopi. Mollusks possess a muscular foot called a mantle, which may be utilised for mobility. The exoskeleton of several mollusks is made of solid calcium carbonate. Another distinguishing feature is the radula, a specialized feeding mechanism present inside the mouths of mollusks. Chitin teeth are utilised to consume or scrape food by the radula.
- Echinodermata: The phylum most closely related to Chordata is Echinodermata. Echinoderms possess an embryonic development in which the anus opening is formed first, then the mouth opening, just like chordates. Unique thing about Echinoderms is that, as juveniles, they are bilaterally symmetrical, but as adults, their symmetry becomes radial.
