99 



Ecology 



Larvae of this species are found in Vostok Bay (Peter the Great Bay) in 

 July- August at a temperature of 15— 23°C. 



The larva of M. truncata has been described by Jorgensen (1945) and Rees 

 (1950). 



SHIPWORM, TEREDO NA VALIS LINNE 



(Teredinidae) 



Veliconcha 



Larvae enter the plankton at the stage of straight hinge. The veliconcha 

 shell is equivalve, equilateral, oval, and dorsoventrally produced. The valves 

 are so highly convex that the larva is almost spherical. The shoulders are short, 

 round, and slope steeply. The umbones are narrow, high, and round. Striation 

 is concentric and distinct. A dark band occurs along the entire margin of the 

 shell and encloses a light-colored band. The shell is heavy and thick. The larva 

 is dark, brown, and opaque. The soft body of a live larva has both red and 

 green pigmentation. The height of the veliconcha shell is much greater than 

 its length (l:h ratio 1.00:1.13). The left valve of the veliconcha has two teeth 

 identical in shape and size. The right valve has three teeth, of which the 

 median tooth is broader than the lateral ones (see Figures 40 and 63). The 

 hinge line is 4-55 |j.m long and the larval shell 70-220 |im (Sullivan, 1948); 

 Imai et al., 1950; Loosanoff e? al., 1966; Chanley and Andrews, 1971). Velig- 

 ers released by the female vary in length from 70-90 |xm. The umbones appear 

 at a shell length of 100 |xm. Metamorphosis usually begins at a shell length 

 of 200 }j,m but may begin at other shell sizes as well: 200 m x 231 m 

 (Loosanoff et al, 1966) and 220 |a,m x 250 |im (Sullivan, 1948). 



Ecology 



Duration of the pelagic stage of development of T. nevalis varies from 

 region to region. At a temperature of 20°C, metamorphosis begins 28 days 

 (Loosanoff ef al., 1966) or 24-35 days (Grave, 1928; Imai et al., 1950) after 

 fertilization. 



Larvae occur in the plankton along the coast of southern Sakhalin (Sea of 

 Okhotsk) and in Peter the Great Bay in the warmest months of the year — May 

 to September — at temperatures of 15-23°C. 



Because of its universal distribution, the morphology and ecology of lar- 

 vae of T. navalis have been described in many works (see above). 



