During the few scorching days of the Newfoundland summer there is nothing quite like a day at the beach. The rest of the year most of us would prefer to be out of the ocean, but most marine animals never want to leave the oceans cool embrace. We are out of our element in cold ocean waters that can chill us to the bone and even drown us because we mammals are adapted to living on land or in water. But there are some hardy animals that live in the intertidal zone at the ocean shoreline that have to deal with life in tide pools, which is neither one nor the other all the time.

Our tide pools are a harsh and forbidding place to live due to our semidiurnal tide, meaning we have two high and two low tides a day ranging from one to two meter sea level changes. When the tide goes out some animals get stuck in pools of water in rock crevices or between rocks: these are called tide pools! Animals that get left high and dry by the tide need to find the refuge of tide pools or be forced to deal with terrestrial predators and the sun’s harsh rays. Most tide pool animals manage to survive our harsh winters only by migrating into deeper water away from the coastal ice!

Despite all that, there are a lot of intriguing species living in the tide pools of Gros Morne, and if you find yourself at Lobster Cove Head, Green Point, or a number of other locations you might be lucky enough to see them in their natural habitat. Remember to check the tide schedule though, if you go at the wrong time you may need a snorkel! To prepare you for your impending tide pool adventure, here is a list of a few tide pool dwellers you may spot.

The Snails

Periwinkles  (1)

Periwinkles!

This may seem like a slow start to the list but it is an appropriate one because the first animal you are likely to see when you get in your car and go is escargot! Periwinkles are the most abundant snail on our shores, their shell is often small, darkish brown, banded, and pointed at the end. If they get caught out of water they can close their shell opening with a cover called the operculum, and when the tide comes back in they can go back to grazing algae off the rocks.

limpet

A limpet snail.

The second type of snail you can see is the limpet. These snails have a different kind of shell that the snail cannot recede into and close the door like a periwinkle can. The shell is conical—imagine an upside down bowl or umbrella in tortoiseshell or white colors—they are very hard to pry off the rocks due to their strong grip.  When tides are high they graze algae and return at low tide to their home-base which is a circular scar on the rock that they etch out with their shell so they fit snugly into for added protection from being knocked off.

Whelk

The dog whelk.

The last kind of snail that is common to this region in the dog whelk, which has a longer spire than the periwinkles and is purplish-brown or creamy white in color; it depends on what they eat. Unlike the other two species of snail, the dog whelk is a predator, it feeds on mussels or barnacles by drilling a small hole through the shell using enzymes and their radula (this is similar to a drill located in their mouth).

Rock Crab or Jonny Crab

rock crabs

Rock crabs.

Hiding in the tide pools under rocks and seaweed you may find the agile rock crab, the reason he’s hiding: gulls love to give them an unwanted sky diving adventure resulting in a meal for said gull. Crabs are mainly scavengers, meaning they will search the sea floor for dead animals to eat occasionally settling for mussel, snail, worm or whatever else they are hungry enough to try. On the beach you may often find what looks like a dead crab, but this is more likely a molt. Crabs grow by shedding their current shell (exoskeleton) and growing a new larger shell, which is soft at first but will eventually harden. The female crabs will carry their eggs underneath their shell so if you notice some eggs on a crab return her with care to the water!

The Common Sea Star

Sea star (1)

Starfish.

The starfish is a favourite amongst many beach walkers and aquarium goers alike; you could say they are the star of the tide pools. This species of starfish has five arms, tube feet on their underside to help them to stick on to surfaces and to walk Sea Stars range in colour from orange, red, brown and green to purple. Believe it or not these sea stars are predators, they will eat mussels, periwinkles and occasionally scavenge for food. To eat a mussel they will wrap themselves around it, pry it open with their tube feet and turn out their stomach into the shell to digest it slowly. If that wasn’t cool enough they can also regrow their arms, or even regrow from an arm! But you need to handle them with care regardless.

The Green Sea Urchin

Sea urchin

Sea urchins.

Sea urchins are a harder, spinier relative of the sea star, around their body they have the same kind of tube feet, and you can also see their mouth on their underside. Their most noticeable feature is the many spikes that protrude from their body, although the spines have no toxins, they will hurt if you step on them so watch out! Kelp is the main source of food for these urchins, that feed using their Aristotle’s lantern (looks like five white teeth) to chew it up. To find urchins you may need to move rocks and seaweed around because they will use their tube feet to grab on to surrounding weeds and stones to use as camouflage.

Hermit Crabs  

Hermit crab

Hermit crab.

If you keep your eye out you may spot a snail shell that is scuttling along the seafloor. Hermit crabs live in the abandoned shells of the aforementioned periwinkle or whelk. You won’t see these crustaceans leave their shell unless they are moving into a new one, which they have to do when they get too large for their current shell. When they are walking around or fighting you will only see their head, claws and a couple of feet moving around.  They keep their soft tail hidden away in their adopted shell where it is safe from predators.

Produced with assistance from the Bonne Bay Marine Station and the Ocean Learning Partnership.

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Alistair Ozon

Alistair is an Environmental and Earth Science student at Dalhousie University, and originally from Dartmouth Nova Scotia. This summer he is working with the Bonne Bay Marine Station, Ocean Learning Partnership, and Parks Canada.