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Wednesday, Sept. 26, 2007

ANIMAL TRACKER

Horned turban shell


* Japanese name: Sazae
* Scientific name: Turbo cornutus
* Description: One of the most prized of all marine gastropods, the horned turban shell — more familiar to sushi aficionados as sazae — has a large, thick, green-gray shell and a snail-like body. The shell has about five spirals, which turn counterclockwise and have horny protuberances. The thickness and shape of the shell and the horns vary greatly according to environmental conditions. The shell-opening is about 3.5 cm in diameter, and is green or red-brown. The inside lip of the shell is not smooth, but rough and granular. It's a kind of marine snail, a sort of conch.
* Where to find them: In relatively shallow coastal waters (up to 30 meters deep) around the Japanese islands from Honshu to Kyushu and Okinawa.
* Food: All sorts of algae. Young horned turban shells eat red-turf algae, while adults eat larger seaweed.
* Special features: The animals spawn from August to September, although the ovaries and testes start to "ripen" from May. The larvae have a very short period as free-floating plankton, just five days or so, and then they settle and start to grow a shell. The planktonic stage and the early shell-growing period are highly dangerous times for young horned turban shells, and many are eaten. Since sazae is such a delicacy in Japan, and commercially important, natural populations are supplemented by artificially reared juveniles. Large numbers of animals are bred and then dumped into the open sea to complete their growth, and this is reducing the genetic diversity of the animal, which may leave it vulnerable to disease. Due to an anatomical quirk of growth, the anus of gastropods is located on the head. They breathe through gills, and when they are collected to eat, they are kept alive for a while so they can clear their gut contents.

PHOTO COURTESY OF BIO-IMAGE NET



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