February, 2000 
SCAMIT Newsletter 
Vol. 18, No.10 
impregnate the other while avoiding it him/her 
self. In the flatworm case, impregnation forces 
the individual into the energetically expensive 
female role. In the examined sacoglossans 
there was a broad spectrum of copulatory 
periods from extremely short to quite long. The 
author points out that long copulations, while 
assuring the success of simple sperm transfer 
methods such as ciliary transport within 
reproductive ducting, expose both members of 
the pair to increased predation and other types 
of risk (dislodgement, for instance) which are 
much less in rapid exchanges. An interesting 
paper. 
Collin (2000) discusses another type of 
sexuality in gastropods, that in which the sex is 
environmentally determined. She considered 
several species of calyptraeids, a group known 
for protandry. Collin investigated the 
conditions under which sex change was 
initiated in members of two types of 
calyptraeids - those that live in stacks, and 
those that live singly. The former was 
represented by Crepidula adunca which lives 
in pair stacks, female larger and below, with 
the younger, smaller male holding onto the 
dorsal side of her shell. Once such a pair is 
established the male sex-change is probably 
suppressed (although the present data are not 
sufficient to show this). A second male may 
also become attached to the shell of the female, 
forming a stable three animal stack. Over 3/4 
of the female C. adunca were in stacks, while 
nearly half the males were. This leaves a 
sufficient number of male individuals to 
undergo sex change into a female without 
drawing on those males already involved in 
reproductive stacks. 
In Crepidula lingulata (Crepipatella dorsata in 
current SCAMIT parlance) only 2% of the 
individuals were involved in female/male 
stacks. In the experiment males kept with 
females were significantly less likely to change 
sex than those kept alone or with other males. 
In some of the experiments both test males 
changed sex, showing the hormonal system 
involved does not always lead to optimal 
reproductive fitness in a given situation. Think 
how severe adolescent angst must be for young 
calyptraeids! The author also made a series of 
observations on the development of the 
species, one brooding eggs to young crawl-out 
(C. adunca) while the other releases swimming 
veligers (C. dorsata ). 
The end of pelagic existence and the adoption 
of life on the bottom for the moon snail 
Polinices lewisii (now Euspira lewisii ) are 
examined by Pedersen & Page (2000). It is 
astonishing how like the benthonic juvenile the 
last veliger is; the only obvious external 
difference is the retention of the veliger lobes. 
Once settled the juveniles rapidly begin 
pursuing a life style similar to that of the 
adults, although more limited to the sediment 
surface. One of the more interesting 
observations was that tiny juvenile moonsnails 
feed not only on tiny bivalves, but also on tiny 
ostracods. Perhaps this is just confusion or 
perhaps they like the variety. If it is confusion, 
it must be very disconcerting to bore through a 
shell only to get kicked in the chops! The 
authors provide a photograph of a snail-bored 
ostracod test in the paper. 
For a long time it has been recognized by 
permitting agencies that one of the more 
obvious impacts of organic discharge is 
bottom-water and/or pore-water oxygen 
depletion from COD, or COD and BOD 
combined. It is instructive to compare our local 
experience with this phenomenon with the 
large scale anoxic/hypoxic occurrences in the 
New York Bight, the Gulf Coast, and now the 
Pomeranian Bay in the Southern Baltic Sea 
(Powilleit & Kube 1999). The authors 
document both the original event, recording its 
severity at a range of sites, and the course of 
recovery of the macrobenthos over time. 
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