The Magic Sail

The Magic Sail

They all fell overboard and drowned.

It was a porpoise that witnessed the event and informed all the other fish in the sea. Eventually a hermit crab reported the details to another of its kind that decided something must be done and, since its fellow crab was smaller in size, it listened to the idea with respect and attention. Also it had the hope of taking over the bigger one’s shell once it had grown out of it.*

The octopus who guarded the entrance of the deepest cave in the water found himself faced with all the creatures in the sea and agreed with them all. It swam into the depths and returned with a silver sail that glowed in the dark.

The newly fitted boat bobbed on the waves and those who had drowned climbed the ladder that hung from its side. They were full of life and congratulated themselves on having survived a watery death.

As soon as a wind arose, they were off and visiting all the places they had planned: islands with white beaches, sea ports with lots to see and buy.

Once they had completed their trip, they set a course for home. So well did their magic sail perform that they sped along just above the waves without a single bump.

* Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell carried around by the hermit crab.

Outside its shell, the soft, curved abdomen of hermit crabs, such as Pagurus bernhardus, is vulnerable.

Most species have long, spirally curved abdomens, which are soft, unlike the hard, calcified abdomens seen in related crustaceans. The vulnerable abdomen is protected from predators by a salvaged empty seashell carried by the hermit crab, into which its whole body can retract. Most frequently, hermit crabs use the shells of sea snails (although the shells of bivalves and scaphopods and even hollow pieces of wood and stone are used by some species). The tip of the hermit crab’s abdomen is adapted to clasp strongly onto the columella of the snail shell.

As the hermit crab grows in size, it must find a larger shell and abandon the previous one. This habit of living in a second-hand shell gives rise to the popular name “hermit crab”, by analogy to a hermit who lives alone. Several hermit crab species, both terrestrial and marine, use vacancy chains to find new shells; when a new, bigger shell becomes available, hermit crabs gather around it and form a kind of queue from largest to smallest. When the largest crab moves into the new shell, the second-biggest crab moves into the newly vacated shell, thereby making its previous shell available to the third crab, and so on. Hermit crabs often “gang up” on a hermit crab with what they perceive to be a better shell, where they will actually pry its home (shell) away from it and then compete for it, and one will ultimately take it over.

Most species are aquatic and live in varying depths of salt water, from shallow reefs and shorelines to deep sea bottoms. Tropical areas host some terrestrial species, though even those have aquatic larvae and therefore need access to water for reproduction. Most hermit crabs are nocturnal.

A few species do not use a “mobile home” and inhabit immobile structures left by polychaete worms, vermetid gastropods, corals, and sponges.

***

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