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Hair ornaments
Hair ornaments Checking with several of the more knowledgeable shell collectors on Okinawa, I have found "E. ogasawarensis" to be just as rare now, as when Mr. Cate wrote his article. However, two more consecutive dives that week, in the same area, produced five more of these beautiful shells for me and one more for Phil. Unfortunately, all the rest of the shells we found, were found in the freshly dead state, laying in the sand at a depth of 115 to 125 ft. Since this is such an uncommon shell for this area, I thought I would share it with the H.S.N. readers, along with the vital statistics for the eight I found [see table]. You will notice they vary quite a bit although all but the one juvenile found alive, are fully mature.
QUESTION: Several years ago, when I lived in Vera Cruz, Mexico, I used to get a lot of sea shells (Macrocypria [sic] cervus) from the fishermen there. These shells were all perfect except for a small hole, which the fishermen said had been drilled by octopuses in order to extract the flesh. They always found a number of empty shells in the dens of octopuses, and these always had the tiny hole. If these holes were made by octopuses, what type could it have been? How would it make such a small hole? R.S., Calgary, Alberta.
ANSWER: Shell boring or drilling by octopuses is a recently discovered phenomenon. Fossil bivalves have been found that were apparently bored in the manner you describe, and recently researchers have found that some octopods bore both bivalves and gastropods. As for species, Octopus vulgaris apparently bores shells and this animal may have been responsible for the bored shells you found. It might also have been Octopus maya, a related species common in the Vera Cruz area. The precise mechanism of boring is unknown, although it probably involves the chitonous radula, a rasp-like organ possessed by octopods and other molluscs. Chemical secretions from the salivary glands may help to dissolve the shell.
The above is from Sea Secrets, Volume 1, No. 1, Feb. 1970. Sea Secrets is published by the International Oceanographic Foundation, 10 Rickenbacker Causeway, Virginia Key, Miami, Florida 33149.
Hair ornaments Where are veligers found and how are they captured? Veligers are found in nearly ail relatively calm marine surface waters on days which are not overcast. On cloudy days, arrow worms, ctenophores and rather plain micro-crustacea predominate. On sunny days, where the surface water is not excessively turbid and choppy, one obtains colorful amphipods, marine worms and a variety of veligers. Areas which yield the highest diversity of prosobranch veligers are those clearwater areas between turbid inshore areas and clear, out-to-sea regions where channels funnel water through a defined region.
A nylon plankton net from 1/2 to one meter at its widest diameter is towed from a slowly moving boat for at least 10- 15 minutes. Mesh size of the net should be no larger than 0.33mm. A wide-mouth jar approximately one liter in volume is secured to the net by means of a hose clamp or twine which may be obtained in most hardware stores. The contents of the sample should be poured through a small fish net (mesh size of 1-2mm) into a bucket containing a few centimeters of fresh sea water. This separates large components such as algae, jellyfish, arrow worms, etc. from the desired smaller components. Then a centripetal effect is introduced by swirling the bucket a few times. After waiting a few minutes for the sedimenting organisms to collect at the bottom, the supernatant sea water and organisms are poured off into another bucket. By repeating this procedure several times, one is able to obtain a reasonably pure sample of veligers.
Photos - Taylor
Fig. 2
Protoconchs of veligers,
Kaneohe Bay, Oahu.
… 1. Cypraea sp.…
o. Cypraea isabella.…
s. Trivia sp., without outer
part of protoconch.…
It is desirable to separate the components in this manner as soon after collection as possible because veligers, especially common species such as Crucibulum spinosum, are capable of secreting appreciable amounts of mucus, which not only aggregates the veligers, but also causes other organisms or pieces of debris to adhere to them. This makes later scanning with a dissecting microscope more difficult and time-consuming. Take one or two buckets of fresh sea water back to the laboratory for subsequent filtration with a piece of nylon cloth which has a pore size of 12µ ( =.012mm). Water filtered in such a manner can be stored for 1-2 weeks without spoilage.
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