Tide Pools of Spectacle Island

The last time I explored tide pools on the Boston Harbor Islands, I was taking Bruce Berman’s Snails to Whales class. We learned the geography of the Harbor, visited the islands, learned about the clean-up, and saw so many creatures I never knew existed in this area. We saw a few of those same creatures on Spectacle Island this past Monday.

Taking cover near a rock, this Asian shore crab (Hemigrapsus sanguineus) does its best to remain hidden. This non-native crab can be distinguished from others in our area by the three “teeth” it has running down each side of its shell. Other species have at least five.

Asian shore crab
Asian shore crab

We surprised another one of these crabs and it stood upright on its back legs, its claws pointed up at us. The red spots on its claws are also characteristic of this species.

Asian shore crab with claws raised
Asian shore crab with claws raised

Common periwinkles (Littorina littorea) shared the rocks with northern rock barnacles (Semibalanus balanoides).

Common periwinkles
Common periwinkles
Northern rock barnacles
Northern rock barnacles

Long-clawed hermit crabs (Pagurus longicarpus) scurried about in their shells, formerly occupied by periwinkles. This one appears to be feeding on seaweed or tiny creatures on the seaweed.

Long-clawed hermit crab
Long-clawed hermit crab

We picked one up and placed it on a rock, waiting for it to emerge from its shell. Its face is a cross between a robot and a gremlin. One claw is much larger than the other.

Long-clawed hermit crab
Long-clawed hermit crab

Rock weed was the most identifiable seaweed growing on the rocks.

Rock weed
Rock weed

We found orange sheath tunicate (Botrylloides violaceus) growing on the underside of the rocks, where it is constantly bathed in seawater. Each orange speck is its own creature, growing in a colony.

Orange sheath tunicate
Orange sheath tunicate

Can you find the creature in the photo below?

It’s a transparent shrimp! We saw a couple of these shrimp floating in the tide pools.

Transparent shrimp
Shrimp

A dead skate had washed ashore. The underside looks like a mask from the movie Scream.

Dead skate washed up on shore
Skate

Areas of salt water ran down patches of sand, creating these shallow channels.

Channels carved by salt water on sand with small stones nearby

The tide pools we found were on the southeast corner of the island. Make sure you visit during low tide!

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