Hermit Crabs (Pagurus spp) are one such organism that toughs it out in the intertidal zone and can range anywhere from shallow waters to upper intertidal, depending on species and location.

There are many species of hermit crabs ranging from Alaska to Mexico. Although usually found in tide pools, they can also be found at depths of up to 50 feet. Hermit crabs feed on plant debris and are such effective scavengers that they have been described as the garbage collectors of the intertidal zone.

Hermit Crab Common residents of rock pools, marine hermit crabs are well known among marine creatures of the intertidal zone for their behavior of inhabiting discarded shells, usually those of sea snails.

Middle Tide Zone: Also called the Lower Mid-littoral Zone. This turbulent area is covered and uncovered twice a day with salt water from the tides. Organisms in this area include anemones, barnacles, chitons, crabs, green algae, isopods, limpets, mussels, sea lettuce, sea palms, sea stars, snails, sponges, and whelks.

When you visit a tidepool and put your finger into a sea anemone, it grabs onto your finger. What is really happening? a.It activates stinging barbs that inject neurotoxin into your skin. 41.

Strategies that organisms have adopted include:

• burrowing into the sand (crabs)
• being covered with thick slime (seaweed and sea-squirts)
• moving with the falling tide (snails)
• clamping down onto a rock (limpet)
• shutting their shells tight (mussels and barnacles).

Sea urchins live only in the ocean and cannot survive in fresh water. They are found from the intertidal to the deep ocean. They then feed on seaweed that washes up into the intertidal by winter storms from the subtidal regions. This may explain why these species are most gravid in the winter months.

The shingle urchin (Colobocentrotus atratus), which lives on exposed shorelines, is particularly resistant to wave action. It is one of the few sea urchin that can survive many hours out of water. Sea urchins can be found in all climates, from warm seas to polar oceans.

Sea urchins are sought out as food by birds, sea stars, cod, lobsters, and foxes. In the northwest, sea otters are common predators of the purple sea urchin. Humans also seek out sea urchin eggs, or roe, for food.

Species have come up with a variety of ways to protect themselves from the sun. The sea urchin is a lowly creature, to be sure. Urchin tube feet are also photosensitive, which means they can sense light.

– A new study has concluded that the red sea urchin, a small spiny invertebrate that lives in shallow coastal waters, is among the longest living animals on Earth – they can live to be 100 years old, and some may reach 200 years or more in good health with few signs of age.

An urchin uses its many tube feet to move along rocks, sand or other surfaces. Surprisingly, an urchin also “breathes” through its tube feet—that’s where gases are exchanged, instead of in gills or lungs. Five toothlike plates, called “Aristotle’s lantern,” surround an urchin’s mouth on the bottom of its shell.

Parasitism – A non-mutual relationship between two organisms, where one species (parasite) benefits at the expense of the other, the host species. In such cases, the sea urchin is the latter species that becomes detrimentally affected by the parasitic species. 🙂 But they were both parasitic to the host sea urchins.

Roundworms, called nematodes, are the most common parasite found in saltwater fish, such as cod, plaice, halibut, rockfish, herring, pollock, sea bass and flounder, according to Seafood Health Facts, an online resource about seafood products operated by the Delaware Sea Grant.