Miniature Knights of the Sea

BY AWAKE! WRITER IN AUSTRALIA

WHALES, dolphins, sharks​—no doubt these imposing sea creatures fire your imagination. The sea, however, holds “living creatures, small as well as great.” (Psalm 104:25) To those with an eye for detail, the smaller creatures are also fascinating to behold.

For example, scurrying across the ocean floor are creatures described as “armored knights of the sea.” Unlike some of their medieval counterparts, many of these miniature “knights” don armor festooned with a fantastic array of colors and patterns. These diminutive denizens of the deep belong to a group of animals called crustaceans and are commonly known as shrimps.

From Plankton to Your Plate

You may think of shrimps merely as delicious seafood. * However, shrimps lead a remarkably varied life before they end up on your plate. Some female shrimps clutch their fertilized eggs to their abdomen until the eggs hatch, while others cast their eggs upon the currents, where they mature independently.

The shrimp eggs hatch into what are known as zoeae and then pass through several larval stages that look very different from the adult form. After spending time among clouds of plankton, zoeae finally settle on the ocean floor and assume their familiar shape, gradually developing into adult shrimps.

Changing the Suit of Armor

How do adult shrimps encased in a sturdy suit of armor manage to grow? “This process (also called ecdysis), involves the formation of a new, soft cuticle inside the old,” says the book A Field Guide to Crustaceans of Australian Waters. “The old cuticle is then shed and the animal absorbs water, swelling the flexible new cuticle to make space for future growth.” The book Australian Seashores explains: “The animal must withdraw its entire body, including all the appendages (and they are many in number), big and strong, or small and delicate, from the old shelly coat. The appendages are pulled out just as one pulls one’s fingers out of a glove.”

How do crustaceans pull large appendages, such as claw muscles, through the narrow gaps formed by the joints? Author W. J. Dakin says: “The performance is possible only because the living parts of the animal are soft and can be pulled through narrow places. Actually, at ecdysis, the blood is withdrawn from the limbs to other parts of the body, so that they can be easily squeezed during extraction.” The new shell retains the swirls, stripes, and blazes of color of the old shell​—and for good reason.

Colors That Camouflage, Others That Advertise

Some shrimps that live among the tentacles of anemones are partially transparent or have suits color coded to match their hosts. These camouflaged shrimps gain protection amid the anemones’ arms and earn their keep by performing housework, removing any debris that may accumulate on the hosts.

Other shrimps are flamboyantly colored, an example being the cleaner shrimps. They often live together under ledges in the reef, and their bright color seems to advertise the cleaning service they provide. Fish that have acquired parasites hover near the cleaner shrimps’ home, thus inviting the shrimps to wander over their bodies. The shrimps even climb unperturbed into mouths and gills. These “shrimp doctors” then remove and eat any parasites and feed on the mucous coat of the fish.

Whatever their color and whatever their role, one thing is certain about these tiny living jewels​—their dress is far more impressive than that of any ancient knight.

[Footnote]

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Hingebeak shrimp

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Transparent anemone shrimp

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Emperor shrimp

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Anemone shrimp

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Cleaner shrimp

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All photos except cleaner shrimp: © J and V Stenhouse