The suction cups on an octopus in a hole in a rock

What’s in the Tidepools? – April 2023

A large pelican with a large long beak in flight.

What’s In the Tidepools? – April 2023

(NPS Photo/P. Geisler)

April’s highlights were brittle stars, sea hares, keyhole limpets, octopus, By the Wind Sailors and Spring flowers. Here is a sampling of what our volunteers observed during this month — thank you to everyone who contributed. Remember to send in your photos; we truly appreciate sharing them with everyone.

Don’t forget to visit the Tidepool Videos page.

A group of small thin armed sea stars on a snady beach.
NPS/P. Raetzman – Brittle Stars

The Keyhole limpet is often found in the tidepools. The soft body consists of a well-developed head. It has a broad and flat foot and a well-developed mantle. This foot exerts a strong suction, adhering the keyhole limpet to the rock. The mantle extends in some species to completely extend over the shell.

They are herbivores primarily feeding on algae. They have a rasping tongue, called a radula, allowing them to scrape the algae from rocks.

The Two-spot Octopus is always a fun find for the visitors as well as the volunteers.

The octopus feeds on Limpets, abalone, snails, clams, hermit crabs and small fishes.

It can grow in size up to 3 feet and live for approximately one year.

This octopus is named for the false eye spot (ocellus) under each real eye. These ocelli are an iridescent blue, chain-link circle set in a circle of black. These false eyes (or spots) are thought to be an adaptation to ward off predators.

The suction cups on an octopus in a hole in a rock
NPS/T. Woods – Octopus

Sea Hares also have a rasping tongue, similar to the keyhole limpet. They are also herbivores feasting on algae

The “horn-like structures seen “rabbit ears” on the head of the sea hare are called rhinophores. (“Rhino” means nose, “phore” means carrier.) Rhinophores allow these animals to pick up chemical scents in the water, such as those from other sea hares during mating season. A sea hare can lay up to eighty million eggs which normally hatch in about two weeks.

Velella velella, also known as “by-the-wind sailor,” is a species of hydrozoan that lives on the open ocean.

It is a small, blue jellyfish-like creature that is only a few centimeters in size. Its body consists of a small, flattened, circular disc that is surrounded by a series of rigid, translucent “sails.” These sails are angled to catch the wind, allowing the velella velella to drift across the ocean’s surface in large, interconnected groups known as “rafts.” It is at the mercy of the wind and the current in order to move.

Although the velella velella is often mistaken for a jellyfish, it is actually related more to the Portuguese Man of War. It is actually a colony of tiny, specialized organisms known as polyps. The colony is made up of a central feeding polyp, which is surrounded by numerous smaller reproductive polyps. It feeds on small planktonic organisms that it captures using its tentacles.

A blue flat oval with a thin sail like feature on the top. The sail is oriented at a 45 degree angle to the oval.
NPS/M. Rose – By the Wind Sailor
A blue flat oval with tiny hairs on the bottom.
NPS/M. Rose – Bottom of By the Wind Sailor

Nudibranchs were plentiful in the tidepools this month. Along with the common ones that are seen, the Hopkins Rose and the Opalescent nudibranch, the Spanish Shawl was observed frequently. If you haven’t seen how the Spanish Shawl moves in the water, check out some of the videos on our Tidepool videos page.

Spring flowers are in abundance thanks to the welcoming rains this year. Make sure you get out and take a look if you haven’t already.

Speaking of Spring flowers, volunteers and staff were treated to a flower and plant walk by Vegetation Technician Patricia. The Volunteer Navigation Committee (VNC) helped to coordinate this walk as part of the Continuing Education goal for the volunteers. We learned about the spring blooms and plants to better inform the visitors at the park. Thanks Patricia!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.