Tidal Touch Zone

Strongyloncentrotus purpuratus

This urchin looks like a pin cushion. That’s because of its round body (called a ‘test’), covered with pincers, tube feet and purple spines that can move to spear food and protect from predators. The tube feet can carry the urchin around rocks or sand, and also pass drifting food down to its mouth.

Urchins use their teeth and spines to dig holes in stones for a hideaway – they can even drill through steel pilings.
Sea otters, sunflowers stars and California sheephead all prey on sea urchins. Without enough sea otters eating them, purple sea urchins can eat up an entire kelp forest.

We also have green and red sea urchins – see if you can find them all.

Pisaster ochraceus

Ochre stars are found from Alaska to California, living among rocks in tidal areas. They come in all kinds of colors: yellow, orange, brown, red or purple. Most have five arms but some have four or seven – like other sea stars, they can regenerate arms.

They eat mussels, barnacles, snails, limpets and chitons by pushing their stomach out of their body and into the shells of their prey. Sea otters and sea gulls are their main predators.

Metridium farcimen

Sea cucumbers live on the sea floor from tidal areas to the deep sea. They do the same job as earthworms do on land, eating detritus and organic matter and breaking it down to recycle nutrients.

Soft and squishy, they have 20 anemone-like sticky tentacles in their mouth, and five rows of tiny tube feet to move around.

Henricia leviuscula

Brilliantly reddish-orange, blood stars have four to six long, skinny arms which can grow up to 10 inches in diameter.

Feeding on bacteria and other tiny particles, they live in protected crevices and pools from the tidal zone down to 2,200 feet between Alaska and Baja, California.

Urticina crassicornis

Look for this red-streaked anemone in tide pools, where it eats urchins, crabs and sea stars. Like all anemones, it has many tentacles which will “hug” your finger as it explores whether you are something to eat or something to defend against!

These anemones also live in the Under the Narrows habitat.

Metridium farcimen

Big and billowing, the plumose anemone comes in many colors: white, orange, tan or brown. They can grow up to 2 feet tall and live for 100 years. They especially love the pilings underneath docks around Puget Sound – look for them on the pilings in our Northwest Waters habitat, too.

They can shoot out tiny stinging cells from their tentacles to snag small zooplankton to eat, and long stinging threads from their gut to defend against predators like sea stars.

Pagurus spp.

Hermit crabs wear discarded shells to protect their soft abdomens. Found in tide pools from Alaska to Baja, California and from the Bering Strait to northern Japan, they have five pairs of legs, including a pair of claws.

One claw, much larger than the other, is used for defense and shredding food (plant material and dead matter); the other is used for eating. The second and third pairs of legs help the crab walk, and the last two pairs hold it inside its shell.