Dr Meyer Rochow bio essay : "When the topic is thirst, a sailor wisdom is definitely on target"

16 Residents in a Sea-Cucumber

A Guinness Book World Record !

Who can spit the furthest, what is the strangest smell, how many individuals fit into a Volkswagen? To find the answers to these and other mind-boggling questions, most people would know that there is the “Guinness Book of Records”, which probably has the answers.

Fewer, however, would know that there is also a “Guinness Book of Animal Records”, but that I actually have an entry in it, is so little known that I felt compelled to write this essay about that feat. So, how did I end up with an entry in the “Guinness Book of Animal Records”?

Let me start with the information that there is a group of marine coral reef fishes of about finger lengths, which enter large starfish and sea-cucumbers in order to reside in these animals’ body cavities. In some languages the usually whitish and rather slippery eel-like fish are referred to as intestinal fish. In Australian jargon they are known as ass-fish, but prudish Americans prefer the politer term “pearl-fish”. Well, these slender marine fish first localize the anus of a sea-cucumber (not a vegetable at all, but an echinoderm animal related to sea-urchins) or the mouth opening of a large starfish (another relative of sea-urchins) by probing, head first, where these structures’ entrance holes to the body are to be found.

The fish then, ever so swiftly, bend their body into a U-shape and slide tail first into the opening. Whether the cavity that from then on they reside in offers them only protection or provides them also with food is still being debated, but it has also been suggested that the fish enter their hosts in order to mate. Being rather crammed and confined to a dark space might heighten sexual arousal (and for these fish may be an ideal setting for romance). While participating at a diving expedition to the South Moluccan Islands with the American research vessel “Alpha Helix”, I occupied myself with these fish and their habits. I collected dozens of large Culcita cushion starfish and sea-cucumbers.

Dissections and analyses of the stomach contents of the fish by the Belgian scientist Dr Jangoux revealed bits of the host’s tissue, but also small zooplanktonic crustaceans from outside the sea-cucumber, suggesting the fish, at least occasionally, leave their hosts and forage for food outside their living shelters.

Regarding my entry in the “Guinness Book of Animal Records”: on a night dive, I collected an approximately 40 cm long sea-cucumber and placed it into a bucket of sea water which was then left in a cold room until next day. The next morning, lo-and-behold, the bucket was teeming with silvery, slender adult ass-fish, 11 of them. Upon touching the sea-cucumber a further four fish appeared and an x-ray of the largest of these, taken at the mammography unit of Waikato Hospital (I was told by the radiologist how refreshing it was to look at something other than the usual) showed that a 16th individual had lodged itself inside the largest fish. 16 in one sea-cucumber! A new world record, because the largest number ever of such fish found in a sea-cucumber in the wild had only been 5, while amongst aquarium-kept fish it had been 14.

In view of the fact that it had been speculated that these fish would enter their living hosts for the purpose of reproduction, I wrote in my ensuing scientific report about the find that, if that was true, one could not help but imagine the orgy that must have taken place inside the sea-cucumber!

parasite manipulation biology science

For more reading about parasites : click for another story : “Parasitic manipulations”

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2016.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

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