Shares Shark's Meal.

Star (Christchurch), Volume XLIV, Issue 600, 2 November 1932, Page 6

Shares Shark's Meal.

Nature Notes

By

James Drummond, F.L.S., F.Z.S.

JT MIGHT BE THOUGHT that the sharksucker is not a swimmer, and that it attaches itself to larger fishes in order to have free trips through the water. The truth, is, it can swim quite well, and so swiftly as to catch up with a shark. Its object merely is to share the larger fish’s meals. Most sharks, Mr E. W. Gudger, an American observer, points out, have sharp, pointed teeth, suitable for tearing, or broad, serrated teeth, suitable for chopping. With these teeth they tear or cut their prey into small pieces. Fragments torn off float in the water. A shark-sucker relaxes the muscles of its sucking disc, lets go, snaps up the fragments, and again fixes itself to its shark, which swims away to seek another meal for itself and for its companion. The shark does not suffer by the relationship. The disc may cause a tickling sensation, but does not harm.

A shark-sucker feeds without giving anything in return, but it takes only the crumbs that fall from the rich man’s table. Although it humbles itself, it is not a parasite.

This type of association, well-known to zoologists, is called commensalism. This is from the Latin “ com,” together, and 44 mensa,” table, and means living at a common table. It is different from symbiosis, which means living together for mutual advantage, and from inquilinism, in which one creature becomes the tenant of another creature without paying rent in any shape or form; and it is very different from opprobious parasitism, common in all parts of the vast and diversified animal kingdom.