May 17
Scalloped hammerhead

Scalloped hammerhead

Species: Scalloped hammerhead (Sphyrna lewini)

Status: Endangered (EN)

Interesting Fact: The hammer-shaped head of the scalloped hammerhead is thought to be a mechanism to spread out the ampullae of Lorenzini which are sensory organs that detect electric currents, chemicals and temperature changes.

More information: The scalloped hammerhead can be distinguished from other hammerhead shark species by the ‘scalloped’ front edge of its head. This species has a relatively slim body and is counter-shaded, with a brown-grey or bronze upperside and a white underside. This relatively large shark can grow up to lengths of 4.3 metres and can weigh up to 152 kilograms. Fish, cephalopods, lobsters, shrimp, crabs, other sharks and rays make up the diet of this species, and prey items are usually eaten whole. Generally occurring in the warm temperate and tropical waters of the Atlantic, Indian and Pacific Oceans over continental shelves, the scalloped hammerhead is also known to enter closed bays and estuaries and generally swims between depths of 0 and 275 metres.

Occasionally caught as bycatch by longline fisheries, the scalloped hammerhead is also caught commercially. Various products are made from the body parts of sharks, including shark fin soup from the fins and vitamins from the liver, as well as the meat which is sold for human consumption. Certain parts of this shark’s range are protected, including the area around Melpelo in Colombia, and there are plans to extend the legal protection to other areas. There are no other known conservation measures currently in place for this Endangered species.

Find out more about marine conservation at the Save Our Seas Foundation and Project AWARE.

Find out more about shark conservation at Bite Back and the Shark Trust.

See images and videos of the scalloped hammerhead on ARKive.

Hannah Mulvany, ARKive Content and Outreach Officer

Apr 20

With Easter just a hop, skip and a jump away, we thought we’d crack into the ARKive coll-egg-tion and have a scramble around to eggs-tract some egg-citing eggs to eggs-hibit in our blog. Along the way, we’ve also learned about the eggs-istence of some rather eggs-centric egg-laying and guarding habits, and we hope you’re as eggs-tatic about our finds as we are!

Gooseberry fool?

Peacock butterfly egg image

Peacock butterfly eggs look a lot like gooseberries!

While you might be forgiven for being fooled into thinking that these green globules are plump and juicy gooseberries, they are, in fact, peacock butterfly eggs. The eggs of this species are laid in groups under nettles, usually in May, and hatch two weeks later.

Sunny-side up? Over-easy? Well-done?

Emu egg image

Emu eggs come in various shades of greenish-black

However you like your eggs, there’s no denying that these ones look as though they’ve been char-grilled in their shells! But fear not, these emu eggs are supposed to look like this; they come in various shades of greenish-black and are the size of a small grapefruit. The male emu is an eggs-traordinary guardian, taking sole responsibility for incubating the eggs over the course of two months while the female wanders off to potentially find another mate, and protecting the chicks against predators for several months once they’ve hatched.

100 kids and counting…

Green turtle egg image

Green turtles can lay an impressive number of eggs per nesting season

In the UK, having more than about four siblings would constitute being part of a pretty large and impressive family, but in the world of marine turtles, this is a mere drop in the ocean. Female green turtles produce between 100 and 150 ping-pong-ball-like eggs per clutch, and can lay up to nine separate clutches per breeding season. While this may seem rather a lot, marine turtles don’t guard their nests or look after their young, and with the threat of land- and ocean-dwelling predators, the survival rate of hatchlings is very low.

High-flying hunger games…

Bald eagle egg image

Bald eagle nests are some of the largest of any bird species

Bald eagle nests, made with sticks and lined with moss, grass, seaweed and other vegetation, are some of the largest of any bird species, sometimes reaching several metres in width. These enormous nests presumably provide a comfy and snug environment for the eggs during the 35-day incubation period, yet things can soon turn ugly. By being bigger and louder, the first-born chick is often afforded more parental attention and food, and will even occasionally kill its younger siblings.

Treasures of the deep

California horn shark egg image

Shark eggs, such as this California horn shark egg, are often referred to as ‘mermaid’s purses’

A mermaid’s purse might well sound like something a sea-dwelling siren would keep her money and credit cards in, but a pilfering pickpocket could get a nasty surprise if they were to try to purloin this particular purse as it is actually a shark egg-case! Mermaid’s purses vary greatly in shape, size and colour, depending on the shark species in question.

Eggs-panding eggs

 

Common frog egg image

Common frog eggs are coated in a jelly-like substance

Frog egg masses, often referred to as frogspawn, tend to look rather like a gruesome collection of eyeballs. The female common frog releases between 1,000 and 2,000 eggs at a time, which are covered in a jelly-like coating. This coating expands when it comes into contact with water, providing protection for the tadpoles growing within.

Egg pasta

 

Sea lemon egg image

Pasta del mar – sea lemons produce somewhat pasta-like egg masses

What may look like a delectable strand of abandoned tagliatelle cast into the depths of the ocean is, in actual fact, a mass of sea lemon eggs. A common sea slug around Britain’s shores, the sea lemon produces thousands of eggs at a time which form a long, coiled, ribbon-like mass. These egg masses are produced in the spring and are attached to rocks, so if you take an Easter weekend dip in the sea and find such a structure, we would advise leaving it well alone and not adding it to your carbonara!

Ha-bee Easter!

 

Honey bee egg image

Honey bee egg

A supplier of sugary goodness and a harbinger of spring to many, the honey bee lays its eggs from March to October. Honey bee colonies have a complex structure, formed of the queen, workers and drones, all of which serve different functions. Worker bees have a variety of roles within the colony, with some being tasked with feeding the developing larvae which emerge from the eggs around three days after they are laid.

Eggshellent parenting

 

King penguin egg image

King penguins incubate their egg on their feet

King penguins appear to take parenting very seriously, with each pair keeping a close eye on their precious egg. Incubation is shared by the male and female and is split into two- or three-week cycles, and parental duties remain shared once the chick has hatched. It’s a good job that king penguins don’t let their eggs out of their sight, otherwise they may not believe the chick belonged to them…the chick looks so different to the adult that they were first described as two completely different species!

Eggs-treme monotreme

Short-beaked echidna egg

A short-beaked echidna egg

While the majority of mammals give birth to live young, there are some eggs-treme mammalian species that lay eggs! These eggs-tra special critters are known as monotremes, and the short-beaked echidna is one of them. The echidna’s leathery egg is laid into a pouch on the female’s abdomen, where it is incubated for about ten days before it hatches. The young echidna, or ‘puggle’, remains there until it is 45 to 55 days old.

We hope you’ve enjoyed these eggs-amples of awesome eggs, and that you all have a wonderful Easter weekend!

Kathryn Pintus, ARKive Text Author

Jan 23

A shocking one quarter of all shark and ray species are threatened with extinction, according to the results of a new study.

Great white shark image

The great white shark is classified as Vulnerable on the IUCN Red List

Threat analysis

The paper, published this week in the open-access journal eLife, analysed the threat and conservation status of an impressive 1,041 species of chondrichthyans, a fascinating group of fish species including sharks, rays, skates and chimaeras whose skeletons are made of cartilage rather than bone. The results were rather alarming, revealing that this group is among the most threatened in the animal kingdom.

The paper is the result of collaboration between more than 300 experts from 64 countries, and reports that, while no species has yet been driven to global extinction, at least 28 populations of skates, sawfishes and angel sharks are now locally or regionally extinct. In addition, several shark species have not been seen for several decades.

Reef manta ray image

Reef manta ray parts are highly valued in traditional medicine, posing a threat to this majestic species

Threat hotspots

The study highlights two areas which are currently experiencing a higher than expected level of threat: the Red Sea and the Indo-Pacific Biodiversity Triangle. The latter is considered to be among the most biologically and culturally diverse regions on the planet, yet unfortunately it is also one of the least regulated.

The authors of the paper explain that, “The Indo-Pacific Biodiversity Triangle, particularly the Gulf of Thailand, and the islands of Sumatra, Java, Borneo, and Sulawesi, is a hotspot of greatest residual threat, especially for coastal sharks and rays with 76 threatened species.”

It is feared that, should no national or international action be taken, these species could rapidly become extinct.

Shark finning image

Finning was revealed to be a major threat to many shark species

Major threats

The results of the study revealed that the main threat to chondrichthyans is overexploitation through targeted fisheries and incidental catches. Of particular concern for the future of sharks, wedgefishes and sawfishes is the process of ‘finning’, which is driven by the huge market demand for shark fin soup, a highly sought-after delicacy in China.

The authors of the new research paper state that, “Fins, in particular, have become one of the most valuable seafood commodities. It is estimated that the fins of between 26 and 73 million individuals, worth US$400-550 million, are traded each year.”

Habitat loss is a further threat to chondrichthyans, with 22 species being threatened by the destruction of estuaries and river systems for the purposes of residential and commercial development, and 12 species being placed at risk due to the conversion of mangroves into shrimp farms. In addition, pollution and climate change have been identified as major threats to sharks, rays and their relatives.

Scalloped hammerhead shark image

The scalloped hammerhead shark is classified as Endangered on the IUCN Red List

Additional factors

As well as providing a vital insight into the type and extent of threats to chondrichthyans, the paper also revealed other interesting factors which come into play. It was found that large body size and occurrence in shallow habitat are the biggest factors determining a species’ likelihood of being threatened. The results showed that with every 10-centimetre increase in a species’ maximum body length came a 1.2-percent increase in the probability that the species would be threatened. Dwellers of deep water appear to fare better than their shallow-water relatives, with a 10.3-percent decrease in the probability of being threatened for every 50-metre increase in the minimum depth limit of the species.

 

Read more on this story at Mongabay.com – One quarter of sharks and rays threatened with extinction.

View photos and videos of chondrichthyans on ARKive.

Read more about shark conservation and conservation in the Indo-Pacific Region.

 

Kathryn Pintus, ARKive Content and Outreach Officer

 

Nov 28

The observance of Thanksgiving Day is primarily associated with the United States, and is a tradition which is thought to date back to colonial times following the safe arrival of the first European settlers to the untamed shores of North America. Nowadays, families and friends congregate to give thanks for what they have, so to celebrate Thanksgiving in our own wild way, we’ve gathered together a few of nature’s special inhabitants that we think owe each other thanks: symbiotic species!

 

Exclusive residence

Common clownfish image

Common clownfish are able to live among the tentacles of stinging sea anemones

Simply speaking, symbiotic species are those that interact in some way, to the benefit of one or both of the critters in question. A classic example, and one that many Disney fans will be familiar with, is the relationship that exists between clownfish and sea anemones.

Sea anemones usually sting fish that come into contact with their tentacles, but clownfish have developed a clever, yet rather gross, method of disguise. By covering its skin in mucus, the clownfish can trick the anemone into thinking it is touching itself, and so does not get stung. In return for a safe place to live and food in the form of debris and parasites found amongst the anemone’s tentacles, the clownfish is thought to scare away fish that may prey upon the anemone, and even lure fish in for its tentacled home to eat – a classic win-win situation! The clownfish is also believed to provide the anemone with good water circulation through fanning its fins as it swims around.

Did you know?

There are different kinds of symbiotic relationships. Some benefit both species involved, and are known as ‘mutualistic’ symbioses, whereas ‘parasitic’ relationships are those in which one species profits at the expense of the other. In some cases, one species benefits but the other is affected neither positively nor negatively, and these are known as ‘commensalistic’ symbioses.

 

Nutritious nectar and pollen parcels

Small garden bumblebee image

Bees, such as this small garden bumblebee, play an important role in plant pollination

Bees feed on pollen and nectar sourced from a variety of flowering plants, with honey bees using the nectar to make their sticky, sugary treat. Although flowers appear to lose out by ‘donating’ nectar, they actually benefit from these flying visits. As a bee rummages around the flower head for food, some pollen gets stuck to its hairy body and legs, and this accidental cargo is then transferred to the next flower the insect visits, pollinating it and enabling the plant to reproduce.

Did you know?

The traditional origin of the modern Thanksgiving Day is commonly thought to be the festivities that occurred at the Plymouth Plantation in Massachusetts in 1621, when the European settlers celebrated their safe voyage, peace and good harvest. However, there is some evidence to suggest that Spaniards in Florida were the first to truly celebrate Thanksgiving back in 1565.

 

Getting a little peckish…

Roan antelope image

Oxpeckers help remove parasites from large mammals such as this roan antelope

In the wilds of the African savanna, large mammals such as this roan antelope can quickly become covered in ticks and all sorts of other creepy crawlies, which doesn’t sound entirely pleasant! Luckily, help is at hand in the form of winged wonders known as oxpeckers. Oxpeckers are known to hitch a ride on the backs of a range of iconic species including hippos, buffalos, giraffe and various antelopes, gorging themselves on ticks, botfly larvae and other parasites – the mammals get cleaned, and the birds get fed, and so this has often been classified as a mutualistic relationship. However, more recent studies have shown that oxpeckers often pick at scabs and cuts to keep them open to get more food, subjecting the wounds to possible infection and potentially harming the host mammal, making this symbiotic relationship more of a parasitic one.

 

Helpful houseguests

Acropora formosa image

Reef-building corals rely on tiny blue-green algae to survive

Reef-building corals provide homes for single-celled blue-green algae known as zooxanthellae, and in return these microscopic plants provide energy-containing compounds for the coral through the process of photosynthesis. The coral uses these vital compounds to build its calcium carbonate skeleton. In a way, these tiny blue-green algae are like live-in coral chefs…and they even clean up after themselves by removing any waste products! Brilliant!

 

Nature’s six-legged gardeners

Leaf-cutter ant image

Leaf-cutter ants tend to their fungus garden by creating ‘mulch’ from leaf fragments

Leaf-cutter ants are known as nature’s gardeners, as they spend their time foraging for leaves and cutting them into suitably sized fragments before transporting them back to their huge underground nests where the leaves are used to cultivate a fungus garden. While the ant colony is entirely dependent upon this fungus supply for food and so greatly benefits from this situation, the fungus benefits by being cultivated by the ants but also loses out by being eaten, and so this relationship could be classified as a more commensalistic one.

Did you know?

Most of us think of the US in relation to Thanksgiving, but did you know that several other countries observe similar days, too? These include Canada, Puerto Rico and Liberia. Additionally, the city of Leiden in South Holland celebrates the traditional US Thanksgiving Day, making the Netherlands the only non English-speaking country to formally celebrate this particular occasion.

 

Food on the go…

Dugong image

Dugong

Loggerhead turtle image

Loggerhead turtle

 

 

 

 

 

 

 

 

Leopard shark image

Leopard shark

Giant manta ray image

Giant manta ray

 

 

 

 

 

 

 

 

Scientists are somewhat divided over whether the relationship that exists between specialised fish known as remoras and a variety of larger ocean species is a mutualistic or commensalistic one. Also known as suckerfish, remoras have a specially adapted first dorsal fin which has been modified into a sucker-like organ. Remoras use this to attach themselves to other marine animals such as sharks, rays, sea turtles and dugongs, feeding on material dropped by the host species while also getting a free ride and protection from potential predators. This seems rather one-sided, but some scientists believe that the remoras may also feed upon certain parasites on the host’s body or gills, therefore providing a great cleaning service to their marine meal providers.

If these beholden bovids, indebted invertebrates and contented chondrichthyans haven’t quenched your thirst for wild Thanksgiving-related information, why not check out last year’s blog, which features a whole host of awesome animals that the first European settlers might have seen upon arriving in North America.

Happy Thanksgiving!

 

Kathryn Pintus, ARKive Text Author

 

Aug 8

As Shark Week continues to float on here in the US, we think it’s the perfect time to shine the spotlight on some of the strangest-looking sharks found on Earth. We all know what the great white shark looks like but have you seen a shark with an ‘executioner’ style hood over its head or one with a beard? Read on to see how many of these bizarre sharks are new to you!

 10. Trendy trim

Photo of leopard shark swimming along sea bed

With a chic patterning of splotches over its body, the leopard shark roams the ocean in the day and night. Despite the fear that all sharks are dangerous, the leopard shark is actually harmless to man and even approachable when it lounges on the sea floor during the day.

 9.  An immense encounter

Photo of whale shark filter feeding, surrounded by other smaller fish

We think this shark merits an appearance on this list just for its sheer size. The largest fish in the sea, the whale shark can weigh up to 13 tons. Perhaps ironically, the biggest fish in the world feeds primarily on some of the smallest organisms, tiny planktonic organisms.

8.  Hard-headed

Photo of kitefin shark swimming

The blunt snout of this species along with its large eyes makes the kitefin shark a perfect addition to our list. The kitefin shark is uniquely ovoviviparous meaning it gives birth to live young instead of laying eggs like most other fish species.

7. Hooded hider

Photo of hooded carpetshark showing spriacle

With a black mask over its head and snout, the hooded carpet shark is said to resemble an eerie ‘executioner’s hood’. The addition of white spots that cover most of its body helps this species to blend into surrounding coral until this nocturnal shark comes to life at night.

6. Wide-eyed wonder

Photo of crocodile shark speciman close up

Check out the blinders on this fish! The crocodile shark is a small slender shark known for its short head and large eyes likely used to hunt effectively at night. Following its prey towards the water surface at night and away during the day, the crocodile shark is an active hunter which enjoys a wide variety of prey including squid, fish, and shrimp.

5. See a saw

Photo of green sawfish swimming

Aptly named, the green sawfish has an elongated snout with over 23 pairs of teeth.  By using this impeccable nozzle, the green sawfish is able to feed on slow-moving fish by clubbing at them with a side of its saw. Cleverly, the green sawfish uses its saw to act as a shovel-like instrument to rake out crustaceans.

4. Face of an angel

Photo of angel shark on the seabed at night

Sometimes mistaken for a large ray due to its appearance, the angel shark has a remarkably flat body and well-placed eyes on the top of its head that are perfect for ambush-style predation. The angel shark is Critically Endangered, likely due to its prevalence in by-catch – the accidental capture of species through standard fishing practices such as trawling. Sadly, this species has been declared extinct in the North Sea.

3. Mega mouth

Photo of basking shark feeding

As the second largest fish in the sea, the basking shark is one to impress. Perhaps a good kisser, the basking shark uses its three-foot-wide mouth to filter feed while it ‘basks’. Not too interested in the social scene, the solitary basking shark is thought to hibernate in deep water.

2. Ancient allure

Photo of filled shark swimming

The frilled shark is one of the most primitive species of living shark. Having perfected its look to have a lizard-like, blunt-ended snout and a very large mouth, the frilled shark possesses an unconventional beauty. Living primarily in the deep-water darkness, this three-foot-long and mysterious beast has had few observations made in its natural environment.

1. Camouflaged charmer

Photo of tasselled wobbegong

Literally meaning ‘well fringed nose with shaggy beard’, the tasselled wobbegong is an exceedingly unusual looking shark. With its branching skin flaps and a lofty lattice-like ‘beard’ the wobbegong’s bristles provide it with a sagacious camouflage and overall appearance. We challenge you to find a weirder-looking shark on ARKive!

Were any sharks on our list new to you? Or do you have a favorite to add to the list? Surf the ARKive site for more sharks and share your favorites in the comments below!

Jade Womack, Education & Outreach Intern, Wildscreen USA

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