Giant barnacles range from northern Mexico to the southern coast of Alaska, including Cook Inlet. While some references describe these as living intertidally and no deeper than 30 fathoms, this species has been found in Kachemak Bay and the Gulf of Alaska in much deeper water and can thrive in water as deep as 300 feet.
Many marine animals use the shells of dead giant barnacles as places of refuge. In Kachemak Bay a small fish called the grunt sculpin (Rhamphocottus richardsoni) makes its home in these shells. With its pointed nose poking out, a grunt sculpin looks just like the beak of a live barnacle.
Observing the outside shell of the barnacle, it may be hard to believe that it is closely related to crabs and shrimps. Glued to a hard surface, such as a rock, by a cement gland on its head, this crustacean uses its cirri to gather food by sweeping the water for plankton. When predators threaten the barnacle, its two large adductor muscles shut each side of the beak tightly. Amazingly, a giant barnacle’s adductor muscles have been found to contain the largest muscle cells known in the animal kingdom. These cells measure 1.2 inches long and .08 inches in diameter — approximately 100 times larger than their mammalian counterparts. This large cell size makes the giant barnacle’s muscle tissue highly suitable for muscle research by professionals in the medical field.
Catie Bursch is a scientific illustrator and education assistant at the Kachemak Bay Research Reserve.
If you have questions about Kachemak Bay, contact reserve staff at 235-4799 or visit the Web at www.kbayrr.org.
[Please include the illustration (attached) by Catie Bursch]
Caption: The Giant barnacle illustrated here was brought up on a longline hook from 80 fathoms of water in the Gulf of Alaska.
They are found amongst the holdfasts of kelp, on rocks, dock pilings and attached to hard-shelled invertebrates, with large groups of giant barnacles often attached to one another. The outer shell shape is typical of a barnacle; however, unlike most barnacles, the giant barnacle’s beak — made up of movable plates — and its pink cirri (claw-like feeding appendages) project above the round, jagged rim of the shell’s opening when the animal feeds.
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