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Thursday, November 22, 2007

Swell Shark

The swellshark, Cephaloscyllium ventriosum, is a catshark of the family Scyliorhinidae found in the subtropical eastern Pacific Ocean between latitudes 40° N and 37° S, from the surface to 460 m. It grows to about 1 m in length, and can expand its body by taking in air or water to make it appear larger to predators.

The swellshark is found on the continental shelves and upper slopes from inshore to deeper waters, preferring rocky, algal-covered areas of kelp beds. It is nocturnal and feeds on bony fishes, alive and dead, and probably crustaceans. Reproduction is oviparous. Swellsharks can live in aquaria for several years and females can lay eggs in captivity. In their natural state they can occur in aggregations while resting, sometimes piled one on top of the other. Sometimes they are caught by sport divers but they are not used.

Wednesday, November 21, 2007

Scalloped Hammerhead

The scalloped hammerhead, Sphyrna lewini, is a hammerhead shark of the family Sphyrnidae. Originally Zygaena lewini, it was later moved to its current name. The Greek word sphyrna translates into "hammer" in English, referring to the shape of this shark's head.

This shark is also known as the bronze, kidney-headed or southern hammerhead. It primarily lives in warm temperate and tropical coastal waters all around the globe between latitudes 46° N and 36° S, down to a depth of 300 m. It is the most common of all hammerheads.

The most distinguishing characteristic of this shark, as in all hammerheads, is the 'hammer' on its head. The shark's eyes and nostrils are at the tips of the extensions. The maximum length of the scalloped hammerhead is 4.3 m and the maximum weight 150 kg.

This shark is often seen during the day in big schools, sometimes numbering hundreds. They are considered dangerous but are normally not aggressive towards humans, in fact most incidents with humans are probably defensive after the shark was surprised or frightened.

This shark feeds primarily on fish such as sardines, mackerel and herring, and occasionally on cephalopods such as squid and octopus. Larger specimens may also feed on smaller species of shark such as the blacktip reef shark, Carcharhinus melanopterus.


Clark's Anemonefish

Clark's anemonefish or the Yellowtail clownfish (Amphiprion clarkii) is a widely distributed clownfish. It is found in tropical waters, in lagoons and on outer reef slopes, from the Persian Gulf to Western Australia and throughout the Indian Ocean and Pacific Ocean as far as Melanesia and Micronesia, and as far north as Taiwan, southern Japan and the Ryukyu Islands.

Clark's Anemonefish is a spectacularly colourful fish, with vivid black, white and yellow stripes, though the exact pattern shows considerable geographical variation. There are normally two white bands, one behind the eye and one above the anus. The tail fin may be white or yellow, but is always lighter than rest of the body.

Clarke's Anemonefish are a popular aquarium species. They are omnivorous, and in the aquarium will readily eat brine shrimp. They will regularly host in many sea anemones in the home aquarium.

Barrier Reef Anemonefish

The Barrier Reef Anemonefish, Amphiprion akindynos, is an anemonefish of the family Pomacentridae. It is native to reefs and marine lagoons of the Western Pacific.

Adults are an orange-brown color with two white bars with black edging encircling the body. The first bar is located on the head behind the eyes and may be thin and broken. The second bar is on the body below the dorsal fin. The caudal peduncle and caudal fin are white. Juveniles are normally brown with three white stripes. In sub-adults the colouring changes to a dull yellow with two white stripes. They have 10 to 11 dorsal spines and 2 anal spines. They reach a maximum length of 9 cm (3½ in) and weigh on average 27.50 g (0.97 oz).