Apr 25

Cephalopods are arguably the weirdest of all marine invertebrates. The name cephalopod literally translates to ‘head-footed’ in Greek, indicating just how strange members of this taxonomic class are, but nothing in their name indicates how incredibly intelligent they are. Their alien-like features are truly fascinating and cephalopods are commonly regarded as the most advanced of all invertebrates!

The weirdest one – nautilus (Nautilus pompilius)

Kicking off our list is the bizarre-looking nautilus, whose appearance resembles a cross between a snail and a shrimp. They are the only species of cephalopod to have retained their external shell, which means they cannot alter their appearance as well as their counterparts.

The invisible one – common cuttlefish (Sepia officinalis)

The common cuttlefish is a master of disguise, possessing the ability to transform its appearance to suit its surroundings in an instant. Check out this amazing talent in this video!

The deadly one – southern blue-ringed octopus (Hapalochlaena maculosa)

This species has one of the most potent venoms on the planet, 1000 times more powerful than cyanide, and there is no known antidote. The blue rings after which this species is named will only appear when an individual is disturbed and serve as a warning before it attacks. The helpless crab in this video finds this out the hard way!

The strangely familiar one – opalescent squid (Loligo opalescens)

You may have come into contact with this cephalopod more than any other – the opalescent squid is more commonly known to us as ‘calamari’. These small squids live in extremely large shoals and hunt by striking their prey with their tentacles.

The one-size-fits-all one – curled octopus (Eledone cirrhosa)

The ability of the curled octopus to transform and camouflage its body is truly fascinating – there is no gap too small or seaweed too colourful for this species! The curled octopus is also equipped with an ink jet they can utilise as a distraction when a predator is nearby. On top of all that, it also has an extremely toxic venom that it uses to paralyse its prey!

The colourful one – Carribean reef squid (Sepioteuthis sepioidea)

Commonly found in shallow reef waters, this intriguing species has enormous eyes and is known to have the largest eye-to-body ratio of the whole animal kingdom! Carribean reef squid communicate with each other by changing the colour of their skin.

The huge one – giant Australian cuttlefish (Sepia apama)

The giant Australian cuttlefish is largest cuttlefish species, reaching lengths of up to a metre.  Despite its large size, this species it is a master of disguise and can easily blend in with its  surroundings due to special pigment cells called chromatophores which allow it to change colour in an instant.

The even huger one – Humboldt squid (Dosidicus gigas)

A close relative of the giant squid, this species, also known as the ‘jumbo squid’, is a monster capable of growing up to 2 metres long and weighing over 50 kilograms! They can move at considerable speeds (up to 24km/h) and have been known to propel themselves out of the water and soar through the air to evade their predators which include whales, sharks, seals and swordfish.

The bright one – firefly squid (Watasenia scintillans)

This bioluminescent species is definitely deserving of a top 10 spot as it is responsible for one of the most spectacular light shows on the planet! Between March and June millions of firefly squid gather off of the coast of Japan, as well as hundreds of tourists, producing a natural spectacle like no other. The firefly squid also uses its bioluminescence to attract prey and select mates.

The strong one – North Pacific giant octopus (Enteroctopus dofleini)

Reaching lengths of up to 5 metres and weighing in at up to 50 kilograms, this monster octopus had to make the top 10! The photograph below is not photoshopped, this species does eat sharks! Its raw strength makes it capable of ripping apart shells and flesh with its tentacles or using its powerful ‘beak’ to make easy work of its prey. This, in tandem with its camouflaging talent, makes it a truly ferocious predator.

Have we missed out your favourite cephalopod? Let us know!

Discover more cephalopods on the Arkive website

Will Powell, Arkive guest blogger

Jun 8
Banggai cardinalfish (Pterapogon kauderni)

Banggai cardinalfish (Pterapogon kauderni)

Species: Banggai cardinalfish (Pterapogon kauderni)

Status: Endangered (EN)

Interesting Fact: The male Banggai cardinalfish broods its eggs and young inside a special pouch in its mouth, and does not eat during this period.

Its striking colouration and long, elegant fins have made the Banggai cardinalfish hugely popular in the aquarium trade. This species is unusual for a marine fish in the extreme levels of genetic diversity between its populations, caused by its very limited ability to move between different areas. The Banggai cardinalfish also lays relatively few eggs compared to other marine fish, and the eggs hatch after being brooded inside the male’s mouth for about 20 days. The young then continue to develop inside the male’s mouth for a further ten days before being released. The Banggai cardinalfish lives in shallow, tropical coastal waters around coral reefs or seagrass beds, and feeds on planktonic crustaceans.

The Banggai cardinalfish is found only at certain sites around islands in the Banggai Archipelago in Indonesia, and is under serious threat from over-collection for the aquarium trade. Many individuals die during transport, and many more are rejected due to being in poor condition. Habitat destruction and the illegal use of dynamite and cyanide in fishing for other species is also a threat to this small fish. A successful captive breeding programme has now been developed for the Banggai cardinalfish, although a proposal to regulate trade in this fish under CITES was rejected due to a conflict of interest. Fortunately, the Banggai Conservation Project is now working to protect the Banggai cardinalfish and its habitat.

 

Find out more about conservation of the Banggai cardinalfish at the New Jersey Academy for Aquatic Sciences and The Mohamed bin Zayed Species Conservation Fund.

See images and videos of the Banggai cardinalfish on ARKive.

Read about World Oceans Day on the ARKive blog, and have a go at our virtual scavenger hunt!

Liz Shaw, ARKive Text Author

Aug 13

With the school holidays stretching out ahead of us and the arrival of summer in the northern hemisphere, many of us will be heading to the coast with friends and family to soak up some sun or play in the sand and surf. The beach is a great place to search for signs of wildlife, and with this in mind we’ve created ARKive’s beach treasure hunt, a bingo style game to keep the kids (and the competitive adults among us) entertained!

It’s so easy to play along, simply print out a copy of our PDF tick sheet, which can also be found on our fun stuff page, then head down to the seaside and start searching.

How many of the following will you be able to find on your next visit to the beach?

Beach Bingo Thumbnail

Crab

Our favourite coastal crustaceans, crabs can be found around the globe, from the common shore crab on the beaches of the UK to the huge coconut crab found on tropical Indo-Pacific islands, thought to be the largest terrestrial arthropod in the world.

Crab photo

Jellyfish

Wobbly they may be, but fish they are not! Jellyfish actually belong to the phylum cnidaria, along with anemones and corals. They can be found in every ocean of the world and are a fairly common sight washed up on beaches. If you do find one, approach with caution, some can give you a nasty sting even when out of the water.

Jellyfish photo

Sharks’ teeth

One of our favourite things to find on the beach is sharks’ teeth. Sharks continually shed and replace their worn-out teeth, with the lost teeth often fossilising on the seabed and eventually washing ashore. Some are very valuable if you are lucky enough to find them, like the teeth of the extinct giant shark megalodon.

Sharks' teeth photo

Urchin

Sea urchins are peculiar looking animals that typically live on the seabed or burrow in to the sand. Many have spectacular looking spines for protection, giving rise to the name ‘urchin’, an old term for their spiky lookalike – the hedgehog.

Urchin photo

Starfish or sea star

Another misnomer here, as starfish are not related to fish but belong instead to a group of animals known as echinoderms, leading marine scientists to use the name ‘sea star’ instead. Sea stars are a fascinating group, most famous for their ability to regenerate limbs. It is estimated that there are around 2,000 species found around the globe.

Starfish photo

Sea shells

Shells of all shapes and sizes can be found on beaches around the world, and the most commonly found are the hard, protective casings of marine molluscs, particularly bivalves such as mussels and oysters, and gastropods like periwinkles, limpets or the even spectacular queen conch.

Shell photo

Driftwood

Driftwood is a common sight on beaches, particularly after a storm. The term driftwood refers to all types of wood washed ashore including both trees and branches washed out to sea naturally or lost during logging, and man made wooden objects such as lost cargo or parts of shipwrecks.

Driftwood photo

Eggs

Many marine species lay their eggs at sea, and it is not uncommon to find eggs washed onto beach from time to time. Some species attach egg clusters to things like kelp (such as the common whelk eggs pictured), while others including sharks and skates lay eggs in distinctive protein cases sometimes known as mermaid’s purses.

Whelk egg mass photo

Seaweed

Seaweed is the name given to a vast array of marine algae, and the different species typically belong to three main groups; brown, green and red algae. Some species have distinctive ‘floats’ or ‘air bladders’ filled with gas to help keep them upright underwater.

Seaweed photo

Cuttlefish shell

Cuttlefish are molluscs, and as such they are related to bivalves and gastropods, the species who produce many of the sea shells we see washed ashore. The shell of the cuttlefish however, is internal, and often referred to as the cuttlebone. It is chambered and filled with gas to help the cuttlefish regulate its buoyancy.

Cuttlefish shell photo

Good luck with your own search – make sure you let us know how you get on! You could even share photographs of your finds on the ARKive Facebook page.

Claire Lewis, ARKive Researcher

May 22

On May 22nd 2012, countries from around the world will celebrate International Day for Biological Diversity (IDB), an annual event aimed at increasing our understanding and awareness of the world’s biodiversity.

A Marine Theme

This year’s theme – ‘Marine Biodiversity’ – provides a fantastic opportunity to raise global awareness of the many issues facing the world’s marine ecosystems, and to encourage practical action to protect and conserve them.

From tropical oceans and coral reefs, to deep-sea vents and the ice-strewn waters of the Arctic and Antarctic, marine ecosystems are hugely diverse. Current estimates of the total number of known marine species range from 250,000 to at least a million, with some scientists believing that the actual figure could be twice as high.

With life in the oceans so incredibly diverse, picking out even a handful of our favourite marine images poses a tough challenge, but we’ve dipped into our ocean imagery to share some of our biggest catches…

Whale shark

Photo of whale shark filter feeding surrounded by other smaller fish

The whale shark is the world’s largest fish, growing up to a staggering 12 metres long and weighing around 12,500 kilograms. Despite their huge size, whale sharks feed almost entirely by filter-feeding on plankton and small fish.

Loggerhead turtle

Photo of loggerhead turtle swimming with a shoal of pilot fish

One of the most widespread of all the marine turtles, the loggerhead turtle is also the most highly migratory, with some individuals having been known to cross the Atlantic and Pacific Oceans.

Nautilus

Photo of nautilus swimming

Nautiluses are often considered “living fossils”, having survived relatively unchanged for millions of years. They are found only in the Indo-Pacific Ocean, where they inhabit the deep slopes of coral reefs.

Blue rice coral

Blue rice coral in shallow reef

The blue rice coral is endemic to Hawaii. Like many other reef-building corals, the blue rice coral is threatened by factors such as bleaching caused by rising sea temperatures, as well as by disease, destructive fishing methods and invasive species.

Sea Otter

Photo of Alaskan sea otter pup eating shellfish

The smallest marine mammal in the world, the adorable sea otter relies on its fur to keep warm in the water. The sea otter’s coat is the densest of any mammal, consisting of around 100,000 hairs per cm²!

Find out more about the International Day for Biodiversity and discover what’s being done to celebrate IDB 2012 in your country.

Explore more marine species on ARKive.

Helen Roddis, ARKive Species Text Author

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