packs it with newspaper to absorb the water from the flesh between the 

 mantle and the valves and ties it down to a board. The paper packing 

 holds the shell in shape but has to be changed 2 or 3 times a day. Most 

 Ischnochitons are light-sensitive and one must turn rocks to find them. — 

 Elsie M. Chace 



COLLECTING SHIPWORMS 



By Ruth D. Turner 



Special publication No. 19, Limnological Society of America, June, 1947 



Shipworms are pelecypod mollusks belonging to the family Teredinidac 

 including the genera Teredo, Bankia, and Nausitora. They are most closely 

 related to the Pholadidae, another family of boring mollusks. They are 

 exceedingly important economically, especially in the tropics where any 

 unprotected waterfront structure made of wood may be destroyed in less 

 than 9 months. In the course of their early development, shipworms have a 

 short free-swimming period during which they are easily distributed by 

 ocean currents. When ready to begin boring they attach themselves by a 

 single byssus thread and then start penetrating the wood, making a minute 

 opening where they enter. Shipworms grow very rapidly and may reach 

 a length of 4 inches in a month; thus a piling which has been heavily 

 attacked by these borers becomes a hollow shell in a remarkably short 

 period of time. 



Though volumes have been written on the history and economic 

 importance of marine borers there is still surprisingly little known about 

 their life history, ecology, and distribution except for Teredo navalis Linne 

 and Bankia gouldi Bartsch, the two species which were so carefully studied 

 by R. C. Miller and C. P. Sigerfoos, respectively. 



The taxonomy of the group is still in a confused state as so much of 

 the early work was done with dried specimens obtained from drift wood 

 and several species were named from shells alone. Most of the characters 

 which differentiate the genera and species in this family are invested in the 

 pallets and largely in the periostracum which covers the calcareous portions 

 of the pallets. It is essential, therefore, that only fresh specimens preserved 

 in glycerine alcohol be used for study as the periostracum sloughs off when 

 the pallets become dry. Distributional records should be taken only from 

 collecting boards or permanent structures as these borers are easily trans- 

 ported from one locality to another by drift wood. 



A monthly collecting panel is made up of 6 to 12 boards and a control 

 supported on an iron bar and suspended in a vertical position with the 

 bottom panel 2 feet above mud line. The boards should measure 12x6x 1 

 inches and be made of pine or other soft wood free from knots. They 

 should be fastened to the back board or iron bar about 2 inches apart 

 with brass bolts. The boards on the panel should be numbered consecu- 

 tively from top to bottom (see figure 1), the control being placed in the 

 center. Thus on a panel having 8 boards the control would be placed 



(51) 



