Monday, January 4, 2010

South Cottesloe - Squid & Port Jackson sharks

28 Nov 2009

Southern Calamari

I can count on the fingers of one hand the number of times I saw squids off Cottesloe. I saw one today that is about 20 cm in length. Its wing flaps/side fins run the full length of its body, suggesting that it's a Southern Calamari (Sepioteuthis australis). Most squids have side fins that are located in the rear half of the body.

I have taken more than a hundred photos of this Southern Calamari, which I found near the end of the groyne of South Cottesloe. It was hanging out in a depth of about 2-3 meters when I saw it. I followed it around the seagrass-covered reef for some time. At one point, when I got too near, it actually got a little aggressive and charged at me.

Port Jackson sharks

This is the second time I saw Port Jackson sharks (Heterodontus portusjacksoni) off South Cottesloe. The last time was on 30 December 2008 (see HERE). Both times it was around the sandy area south of the South Cottesloe groyne, about 100 meters from shore, and at a depth of 4-5 meters.

I saw three today but they were sitting quite far apart to get all three in the same photo.

These blunt-headed, lazy-looking sharks are about 30-40 cm in length. Adult Port Jackson sharks (PJs) can be more 75 cm long.

PJs are more active at night, being nocturnal feeders. They feed on sea urchins, crustaceans, moluscs and fishes. Their genus "Heterodontus" means "different teeth". Unlike most sharks which have pointy, cutting teeth, PJs have front teeth that are small and pointed and back teeth that are broad and flat. These teeth allow PJs to crush and grind the shells of sea urchins and moluscs.

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