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African penguins are found only off the coastlines of South Africa and Namibia. South Africa has two land-based colonies, one in Boulders Beach and the other in Betty's Bay.

Like sharks, rays have cartilaginous skeletons. These flat fish have gill slits on the ventral (under) side of their bodies. Two spiracles behind the eyes on the dorsal (upper) surface draw in water which flows over the gills before exiting through the gill slits.

Cuttlefish are related to octopus and squid. The common cuttlefish is also known as the ink-fish.

Like octopus, cuttlefish can change both their body colour and texture in response to their environment and their survival needs.

Special cells (chromatophores) located in the outer-skin layers, contain colour pigments, which the animal can alter by neural control (merely by thinking about it!). These chromatophores typically occur in red, yellow, brown, black and blue, and each can be expanded to display a large area of colour, or contracted to a tiny speck.

Common cuttlefish are the largest cuttlefish species found in southern Africa and occur from Mozambique on the east coast to the mouth of the Orange River on the west coast.

They live in sheltered lagoons and estuaries and in the open ocean to depths of 200m.

Cuttlefish have tentacles including two longer ones that are hidden in ‘’pockets’’ under the eyes. They use the long tentacles during mating and for capturing their prey.

Cuttlebones on the beach

Most people are familiar with cuttlebones, which are found washed up on the beach and given to pet birds as a dietary supplement and to sharpen their beaks.

Cuttlefish use the cuttlebone to regulate their buoyancy.

The giant spider crabs in the Atlantic Oceans Gallery were collected by Tokyo Sea Life Park in Japan and sent to the Two Oceans Aquarium.

Spider crabs are the largest crustaceans in the world – males grow to approximately 1m in length with a 4m leg stretch. These crabs live at depths of approximately 400m and in temperatures between 11ºC and 14ºC.

Marine mystery

Very little is known about the biology of giant spider crabs. It is virtually impossible to determine their age and we do not know when they reach sexual maturity. Their breeding habits are also a mystery to marine biologists.

Moult to grow

As with all crustaceans, continual growth is impossible for giant spider crabs because of their hard exo-skeletons. To grow, the crabs have to shed this exo-skeleton by moulting. This is a complicated process which can take up to two days. Each moult is potentially life-threatening as the crab can become entrapped in its old shell. Even if the moult is successful, the sheer effort is sometimes so exhausting, that the crab dies soon afterwards.

Vulnerable to predation

With its “new” soft, elastic exo-skeleton exposed, the crab is vulnerable to predation. The new exo-skeleton expands rapidly as the crab “pumps” water into it. Over time, together with a combination of enzymes and calcium carbonate, the new skeleton hardens. The water is then “pumped” out again and the crab grows into its new “coat”.

Cursed by lobster fishermen for the quantities of slime they produce when startled, these oceanic oozers secrete a white fluid which expands rapidly on contact with seawater, producing enough slime to fill a 7-litre bucket in minutes.

The sticky substance adheres to predators, forming a suffocating layer over their gills. The slime also creates problems for the hagfish itself, but it has developed a manoeuvre which allows it to escape – it knots its tail and, twisting the knot over its body, scrapes off the offending slime.

Although they look like snakes, hagfish are not snakes or eels, but belong to a unique group of animals.

They are primitive animals that have no jaws, no eyes, fins or scales. They have a cartilaginous skeleton and pouch-like gills not seen in any other living fish.

Living fossils, the species have changed little since the days of the earliest hagfish, which date back some 330 million years.

Scavengers of the deep

Hagfish have horny dental plates which rasp and tear into soft flesh, carrying pieces back into the mouth. A fang above the plates holds the live prey in place while it is shredded. Since they have no teeth hagfish cannot eat scaly fish and therefore they only feed on small live fish, on soft rotting carcasses or on animals that other animals have already opened. When larger food items are found, such as dead whales, hagfish have another strategy – they enter the giant corpse and eat the soft tissue out from within.

Hagfish play a vital role in recycling dead animals on the seabed and may occur at surprisingly high densities, with some areas having over 50 000 animals per square kilometre.

Box jellies are found off the west coast of South Africa and are often encountered in swarms by scuba divers.

Named for their ghostly, transparent bells, moon jellies have short tentacles that are armed with stinging cells or nematocysts. Fortunately, their sting is not as toxic as that of other jellies.

The longsnout pipefish (Syngnathus acus) is found throughout South African waters. It occurs in the waters off southern Africa from Walvis Bay to the Thukela Bank on the Kwa-Zulu Natal coast.

Life depends on plankton. Plankton is made up of microscopic plants (phytoplankton) and animals (zooplankton). Zooplankton feed on phytoplankton and drift with the currents.

You’re probably thinking, “Wow, look at the size of these guys! Yum!” These West Coast rock lobsters (crayfish or ‘’kreef’’ as they are known locally) are approximately 30 years old! The chances of you seeing crayfish this size in the ocean these days are minimal. Rock lobsters grow very slowly and can live to the ripe old age of 50 years or so.

Also known as the double sash butterflyfish, this is the only butterflyfish species to be found in both the Indian (warm) and the Atlantic (cold) oceans.

The South African butterflyfish is endemic to our coast..