THE NATURALIST. Carious Partnerships.

Otago Witness, Issue 2892, 18 August 1909, Page 76

THE NATURALIST.

Carious Partnerships.

Many humble creatures enter into partnerships as well as human beings. These partnerships are for mutual welfare, and are entirely distinct from those cases of parasites, where one creature simply preys upon another. In the real partnerships mutual help is given, and the creatures become true messmates.

— Crab and Mussel. —

An extraordinary partnership exists between a little crab and the mussel. This crab, the Pinnothere, is a very warlike little creature, and in return for lodgment within the mussel's shell he allows his landlord a certain amount of food. This, therefore, is an excellent arrangement, as the mussel is always well fed, while- the crab is provided with a splendid castle. That is to say, the crab has a home which costs him nothing in building and repairs. This partnership is of an extremely intimate character, as the mussel appears to do exactly as the crab orders, opening and shutting the shell at desire.

In fact, the mussel to a certain extent acts as a motor car with the crab as the engineer; the car transports the engineer to various parts at' will. Theft the crab leaves his shelter for a time while he goes hunting. Should the tables be turned, and he become the hunted, he rushes to the mussel, which at once- opens its shell, and immediately closes it as soon as the crab retires.

Any focd he cannot devour becomes the perquisite of the peaceful little mussel. The weaker creature thus thrives on the crumbs which fail from the table of the fierce Pinnothere.

—The Hermit Crab.—

An even stranger partnership exists in the case of another species of hermit crab, th© Pagurus Prideauxii. This crab goes into partnership with a beautiful sea anemone called the Adameia, but he is a very chivalrous little creature, as he gives all the tit-bits to his host. When he ha« finished fishing he picks out all the most dainty morsels, and sees that the Adamsia has a good feed before he commences his own meal.

Stranger even than this, he will never willingly part with the Adamsia, while should he be deprived of his partner he becomes restless and ill. He displays the utmost solicitude bhat his host is not hungry. More than this, when he finds a more suitable shell he doe-5" all he can to persuade the Adamsia to enter the new home; besides using all manner of endearments, he helps his host in every possible way, assisting it to detach itself from the old shell.

Should the Adamsia not be satisfied in any way with its new dwelling, the little crab will redouble his efforts until he finds one which is suitable to hia host. So €oon as this is done, the crab at once goes in search of fresh dainties, co that he may reward the Adamsia. for the inconvenience to which it has been submitted.

Strangely enough the same shell frequently contain a third lodger, and 1 * the little community live in perfect concord. The other r-reaturc is a fat pink worm, which usually occupies the attic — that is, the Tnside woint of the shell, and which livft= and thrives upon the food brought by the crab.

— A Strange Partnership. —

Another crab becomes partner in a shell with a horrible creature possessing a squirming, worm-like body armed with terrifying appendag-ss which inflict _ dangerous wounds. This partnership is as different as could be imagined when compared with the former.

Th-e fearsome pair inhabit -what appeaxa to be a harmless 6hell covered with moss. From out of ihe shell come a einuous, waving ma«-> of arms, beneath which are the appalling claws of the crab. Woe unto any creature which comes near; the arms enclose it, and the claws of the crab drag it to destruction. So the horrible pair in their pirat? %e^3l move along, creating a veritable hecatomb amongst the unsuspecting cieatur-es around.

Certain kinds of sponges go into partnership with -crabs, Ihe 6ponge being borne about to various places, while the crab i 3 provided with an efficient disguise. There are innumerable little- crabs which become the mess-mates of other creatures ; as a result big bivahes are really hotels for the tiny pea-crabs. In the case of the biggest f-hell-fish known, the tridaena, as many as a dozen, crabs may take refuge in its armour.

— "Weak* and Strong. —

Cases are known where two creatures of the same eort go into partnership. For instance, a weak Semat frequently joins forces with a stronger brother, and the partnership ie of great value to both. They

become mess-mates, and enter into on* another's troubles and joys. Those peculiar creatures, Cirripedes, are usually found in association with whales, where they possess secure homes and a constantly changing diet. That curiouslooking object, the trepang, goes into partnership with a ghost-like silver fish which dies as soon as the partnership ;s; s dissolved. One of the starfishes goes into partnerhip with the sea lily, while iteelf giving harbourage to small fishes.

Shrimps frequently go into partnership with other creatures. For instance, jellyfishes contain under their bodies- tiny transparent shrimps which never by any dhanoe are injured by the tentacles of their host. One jelly-fish has as a partner a. tiny seaminnow. Some of the smaller mackerels go into partnership with the Nautilus.