Opisthobranch of the Week Data
Notarchus indicus, a small attractive aplysid is found on Okinawa in association with the green alga Caulerpa. The animal is considered to be rare here in as much as only three animals have been collected as of the current date (March, 1999); several others have been seen but neither photographed nor collected.
Notarchus indicus has a remarkable adaption which allows the animal to move quite rapidly, at least for short distances. The parapodia are nearly completely joined, allowing a relatively large cavity to be formed within. Water is drawn into the cavity between the parapodia, providing quite a distended appearance of the animal's entire body. If the water is rapidly expelled, the animal is propelled by a series of somersaults while at the same time taking in additional water. It is more than a bit entertaining to watch the (escape?) antics of this delightful little aplysid.