(Isopoda)
Isopods have a flat, mottled dark grayish-green segmented body, 12 legs, a short, forked tail, and two long searching antennae. As you can see in the photos, these antennae are almost as long as their bodies, which are about 2.5 cm. This marine creature is a member of the isopod family. You can find these isopods in intertidal areas along beaches in the Pacific Northwest, including here on Vancouver Island, B.C. I see them on the West Coast far more often than on the East Coast of the island.
The Ligia occidentalis uses gills to breathe which are located in the rear end and even though it spends most of the time out of the water, it has to make its way back to the water to breathe on a regular basis.
They feed at night on different kinds of organic matter that they scavenge from rocks and pilings. It will spend the daylight hours hiding under rocks. It is eaten by seabirds and other small creatures that can catch it, it can run quite fast.
The females emit a pheromone to attract males, the males then produce a package of sperm to fertilize the female’s eggs. The female can produce an egg case with up to 100 embryos in it. The average lifespan of these isopods is about a year, but they can reproduce as many as eight times during their life.
Beach isopods are scavengers, nibbling on whatever recently died on the rocky shore. At low tide, they swarm over the beach looking for the recent dead. Isopods can be found under rocks or clinging to the holdfasts, stalks, or blades of seaweed at high tide. They are also sometimes found in mussel beds.
Isopods have a myriad of different predators that include foraging gulls, shorebirds and fish.