Tag Archives: Molluscs

Crown-of-thorns sea star and its nemesis

crown of thorns

giant triton snailCrown-of-thorns sea stars (Acanthaster planci) feed on coral and, because of this, are considered a menace to the health of coral reefs. Up to a foot-and-a-half across, they can have as many as 19 arms and are covered by venomous spines. If this all sounds like this creature is a nasty piece of work, the good news is that it has not caused extensive damage to the reefs here in Hawaii.

The crown-of-thorns does have predators, one of which is triton’s trumpet (Charonia tritonis). These large triton snails, up to 20 inches long, feed on echinoderms including crown-of-thorns sea stars. When they scent prey, they will take off after it and are considered speedy for a snail. When a triton’s trumpet catches its prey, it grips it with its foot and applies saliva that causes paralysis, which allows the snail to consume its meal without further drama.

Varicose phyllidia

Varicose Phyllidia

This colorful little creature is a sea slug. As with many other nudibranchs, the bright coloring serves as a warning. They’re poisonous and, because of this, have no known predators. One tidbit I found interesting is that nudibranchs like this Varicose phyllidia, don’t produce their own poisons. Instead, they ingest toxins from their prey, such as sponges, and recycle it. So not just yellow and black and pale blue, but green as well.