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Sunfish: giants of the deep. Photo courtesy Cape Argus Sunfish: giants of the deep. Photo courtesy Cape Argus

Gentle giants

  • Sunfishes are so called because of their habit of drifting at the surface as if basking in the sun.

  • There are two species of sunfishes found in the waters surrounding Cape Town: the ocean sunfish (Mola mola) and the sharptail sunfish (Masturus lanceolatus).

  • Ocean sunfishes are found in all the oceans of the world, excluding the icy polar seas. Sharptail sunfishes are found only in warmer waters, thus they are extremely rare in the local waters. Only ocean sunfishes have been displayed in the Aquarium.

  • Both species attain a similar size of 3m in length and a weight of 2 000 kilograms.

  • Sunfishes are the largest bony fishes in the ocean.

  • Sunfishes do not have tails as other fishes do – the caudal (tail) fin has been replaced by a rudder-like structure. The ocean sunfish has a rounded, wavy rudder. The sharptail’s rudder, as the name suggests, has a distinct point.

  • All sunfishes have small mouths and the teeth are fused together in each jaw, forming a beak like that of a parrot.  The beak is internal and hidden from view.

  • Sunfishes feed on jellies.  It is remarkable that an animal that grows to such a large size subsists on a diet with very little nutritional value.

  • Sunfishes are not considered edible as they consist mainly of cartilage and gristle and their flesh is soft and insipid.  Also, the skin is extremely rough, similar to sandpaper in texture.

  • They are the most fertile of all fishes, producing up to 300 million tiny eggs.

  • The name ‘mola’ is derived from the Latin word for millstone because of their similar shape.

Click the link below to download a research paper about sunfish that appeared in the Journal of Experimental Marine Biology and Ecology.

For more information, visit www.oceansunfish.org/research2.html.