The Elephant Fish

It’s not an elephant or a (bony) fish and although it’s sometimes called the elephant shark, it isn’t a shark either. They can also be referred to as ghost sharks, but they are nothing like those in the movieCallorhinchus milii  are similar to sharks and rays in that they have cartilaginous rather than bony skeletons, but belong to the order Chimaeriformes.

They can be distinguished from sharks by  their gill slits being covered with a skin (operculum), leaving a single opening on each side. Chimaerids also have smooth skins without the dermal denticles of sharks. They also have a single spine in front of their first dorsal fins, which can be laid flat as in bony fishes. Their heads are grooved with lateral lines and their upper jaws are fully fused to their heads, unlike in sharks where the upper jaw is only loosely attached to the skull. Their teeth are modified to form flattened crushing plates with sharp cutting margins; two pair in the upper jaw, and a single pair in the lower jaw.

Male chimaerids have the normal claspers or intromittent sexual organs that are present in the sharks and rays alongside their pelvic fins, but they also have a second pair of flat, retractable claspers in front of the pelvic fins. These are usually armed with hooks and are probably used only to grip the female during mating. There is also a club-like frontal clasper on top of the head. All chimaerids are oviparous, laying large eggs in a horny case which is deposited on the bottom. Like most sharks and rays, development is slow and the young do not hatch until six months to a year after the eggs are laid.

C milii lives along the continental shelf off Southeastern Australia and around the New Zealand coast to depths around 200m. Their size ranges from 70-125 cm (4 ft).

The most unique thing about this animal is the fleshy protuberance on the head that is has sensory pores that detect movement and weak electrical currents in its search for small shellfish on the seabed.

Beautiful aren’t they.

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