Thursday, December 8, 2016

What is That Scurrying On the Sand?

August 8th was a cloudy day with a few sprinkles in the morning at Haystack Rock. Katie Corliss, lead interpreter, along with three additional interpreters were on the beach for the 1.5 ft low tide at 11:13 am. Over five hundred visitors experienced the Marine Garden during the five hours the interpreters were on the beach.

Katie captured a great video of mole crab activity in the sand. In the genus Emerita they are crustaceans commonly known as mole crabs, sand crabs or sand fleas. Related to hermit crabs and stone crabs, the mole crab spends much of its time buried in the sand. It is well camouflaged by its gray shell, burrowing quickly and frequently into the sand. The crab lives in the area of breaking waves, moving up and down the beach with the tides. It feeds by filtering tiny plankton from receding waves using a sweeping motion of an antenna. Check out the video of the crabs scurrying in the sand and burrowing in.

video



Mole crabs are less that 2 inches in length and can be found along the entire west coast of the US from Alaska to Baja California. Their life span is rarely more than 2 to 3 years and they can reproduce in their first year producing bright orange eggs. Next time you are at the beach, look closely down at the sand near the tide line for these scurrying crabs.

Friday, December 2, 2016

Opalescent Nudibranch In The Sand

Today we look back to August 3rd on the beach. Gina Palmer was the lead interpreter on the beach for the 1.4 ft low tide at 7:46pm. It was a sunny afternoon with a NNW winds between 15 and 25 knots. The opalescent nudibranches, typically found under the boulders in the central pools of Haystack Rock, were today out in the sand.


Opalescent Nudibranch 

The opalescent nudibranch (Hermissenda crassicornis) is an invertebrate that resides in the intertidal rocky shores from Baja California to Alaska. They grow to about 3 inches, subsisting on a diet mainly of hydroids, but will also eat small sea anemones and bryozoans.  A nudibranch lives for a maximum of one year and is hermaphroditic. It's eggs are laid in narrow, coiled strings attached to eelgrass or algae. 

The opalescents are a colorful species of nudibranch, having bright orange areas on their back with a blue line on each side. Next time you're in the intertidal zone at low tide - anywhere on the west coast -take a look in the sand or under boulders for these colorful invertebrates!