Black Tegula Snails (Chlorostoma funebralis)
(formerly known as Tegula eiseni.)
Contributed by TPERP Carol Holt
Where to find them: Their range is along the Pacific Coast from Vancouver Island to Baja California in the upper and middle intertidal zones.
What do they eat: This species is an algal grazer on microscopic films, attached algae and wrack. The animals prefer soft algae such as Macrosystis. They will also feed on larger bits of kelp, Nereocystis, and Mastocarpus, that wash into the tidepools. They eat their food when it is submerged.
Who eats them: They are a favorite dietary item for predatory snails, octopus, rock crabs, and ochre sea stars. Many fish also find them tasty and, consequently, they can be used for bait. Many people consider black tegulas to be a great delicacy. They are especially a delicacy in Italian cuisine.
Adaptations: They normally crawl along at a pace of about 0.6 – 0.8 mm/sec but can double this speed if they encounter or are pursued by an ochre sea star. They may act to escape a predatory snail by climbing on top of the other snail’s shell. When fleeing a predator on a sloping surface, the black tegula simply detaches itself and rolls down the rocky slope.
Reproduction: These animals are sexually dimorphic. They are capable of spawning multiple times in a year and do so frequently in the southern end of their range. But those inhabiting the northern portion of their range (such as the coastal areas of Oregon and Washington) usually spawn just once a year in late summer or fall.
What is their life like: The snails cruise through their environment on the hunt for their usual diet of algae and microscopic films, which they harvest using an elaborate arrangement of hooked teeth in their radula, which fan out from their mouths. They must be on constant alert for their many predators. The animals can live up to 5-8 years in the southern end of their range and up to 30 years in the northern end.
Interesting Facts: The black tegula snail often serves as a “hotel” of sorts for the slipper snail (Credidula adunca) and the symbiotic limpet (Collisella asmi) who like to attach themselves to the top of the black tegula’s shell.
An empty black tegula shell is a popular home for hermit crabs.
As mentioned earlier, the black tegula snail is considered a delicacy in Italian cuisine. The snails are cooked, shells and all, in oil and the meat is removed from the shell using a toothpick or a pin.
Sources of Information:
Brandon, Jeffrey L. & Rokop, Frank J. 1985. Life Between the Tides.
San Diego: American Southwest Publishing Company of San Diego
Ricketts, Edward F., Calvin, Jack, and Hedgpeth, Joel W. 1985.
Between Pacific Tides Fifth Edition. Stanford: Stanford University Press
Denny, Mark W. & Gaines, Steven D., editors. 2007.
Encyclopedia of Tidepools & Rocky Shores. Berkeley: University of California Press
Sheldon, Ian. 2007. Seashore of Southern California. Auburn: Lone Pine Publishing
Last revised 29-Jul-13