Elephant Shark aka Australian Ghostshark

Elephant Shark The Elephant Shark or Australian ghostshark (Callorhinchus milii) is a cartilaginous fish (Chondrichthyes) belonging to the subclass Holocephali (chimaera). Sharks, rays and skates are the other members of the cartilaginous fish group and are grouped under the subclass Elasmobranchii. Alternative names also include makorepe, whitefish, plownose chimaera, or elephant fish.

The ghost shark is easy to recognize due to the small club-like structure located on the snout. The mouth is located just behind the snout and the eyes which are often green are large and set high on the head. There is a single gill opening immediately in front of the pectoral fin origin on each side of the fish. The pectoral fins are large, providing a primary means of locomotion. There are two widely spaced dorsal fins. There is a spine located just anterior to the first dorsal fin; the first dorsal fin is much taller than the second dorsal fin and the anal fin is taller than the caudal fin. The caudal fin is broadest at the lower lobe origin and lacks a caudal filament. The upper lobe of the caudal fin is much longer than the lower lobe.

The body is silvery white, similar to aluminum foil in color and occasionally has dark markings posterior to the eyes as well as on the fins.

It is found off southern Australia, including Tasmania, and south of East Cape and Kaipara Harbour in New Zealand. This chimaera resides on continental shelves of cool temperate areas to depths to at least 656 feet (200 m). It has also been reported to migrate into estuaries and inshore bays during the spring months to mate.

The maximum reported size of the ghost shark is 49 inches (125 cm) total length. Males reach maturity at 2-3 years of age, corresponding to 19.7 inches (50 cm) total length, while females mature at 4-6 years of age and 27.6 inches (70 cm) total length. The lifespan of the ghost shark is approximately 15 years.

The club-like projection on the snout of the ghost shark is used to search for prey. The end is covered in pores that sense movement and weak electrical fields. Ghost sharks feed primarily on shellfish and molluscs including the clam Maorimactra ordinaria.

The ghost shark is oviparous. Two keratinous egg cases are released during the spring months onto sandy or muddy bottoms in shallow water. The egg cases measure up to 25 cm in length and 10 cm in width and are golden yellow in color. During the following 8 months, the embryos remain in the egg cases feeding solely on yolk. The coloration of the egg case changes through time, from golden yellow when first released by the female to brown and black prior to hatching. When the young hatch, they measure about 15 cm in length. They will move from the shallow water nursery area to deeper water as they grow.

This fish has three cone pigments for colour vision (like humans); its dorsal fin has a very sharp spine. The spine has been reputed to be venomous, but no serious injuries have yet been reported.

Predators of the ghost shark include larger fish including sharks.

 
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