The sea hare, or Anaspidea, is a species of gastropod mollusk and marine snail of the class Gastropoda. It is one of the more interesting creatures in the animal kingdom. The common name, sea hare, originates from its appearance. The rhinophores, or spouts, that stick out from its head resembles the ears of a hare, or rabbit ears.

There are different types of sea hares depending on where they are found. The aplysia californica, or California sea hare, is one of the most common of these. They are sometimes known as the California black sea hare depending on their conditions.


The sea hare is a fairly large creature, with its largest species reaching up to 31 lbs or 14 kilograms. The aplysia Vaccaria also can have a length of 30 inches or 75 centimeters. However, on average, the typical species of sea hare ranges from 7-20 centimeters.

They have soft bodies within a small internal shell and no external shell. This shell is made from various proteins, is thin, and has a small mantle cavity. Although this may seem to be a vulnerable situation to be in, they have plenty of other ways to protect themselves.

Sea hares can be found off the California coast
Sea hares can be found off the California coast


The main element of the sea hare’s diet is seaweed and algae. Similar to its toxic ink, the sea hare’s body color is dictated by the color of the seaweed it eats. The pigment has an impact on many functions. For example, a sea hare feeding on green seaweed or sea lettuce will appear in a green pigment.

The sea hare plays an important role in maintaining its habitat through the consumption of algae. By feeding on algae, dangerous overgrowth is minimized, and toxins released by algal blooms are then reduced. They feed on various types of algae, such as green algae and red algae. Similar to seaweed, the color of algae impacts the appearance of the sea hare.


Sea hares typically inhabit shallow water depths and are mostly found on rocks or around seaweed. They have also been known to place themselves beneath the sand and leave only their rhinophores exposed. This is particularly true with juveniles. They are known to be fairly mobile creatures as well, although somewhat unpredictable. They can utilize their ‘wings’ that are made of jelly-like skin, which allows them to create some locomotion in the form of jet propulsion.


The sea hare is very similar to a lot of mollusks in the sense that they are hermaphrodites. They have both male and female reproductive organs. Sea hares are known to expel pink, chain-like eggs when they are reproducing.

The brown sea hare is one of the many types of Anaspidae
The brown sea hare is one of the many types of Anaspidae


Human intervention is one of the threats that the sea hare has to contend with. In some cuisines around the world, the sea hare is a delicacy. For example, in Chinese cooking, the sea hare is prepared in a sauce with other seafood and served. In Hawaiian culture, it is referred to as kualakai, a dish prepared with leaves.

The Anaspidea has always been of interest to researchers. This poses an issue for them. They are studied in neurobiology and looked at regarding memory and learning.

As for threats from other animals, the sea hare has many efficient systems in place to protect them from predation. Their main predators are starfish, lobsters, and bigger gastropods. Their skin is fundamentally toxic and makes them a less than appetizing prospect for many predators.

Their other defense mechanism is equally as poisonous. When the sea hare is disturbed or under threat, they’re capable of releasing a powerful toxic cloud of ink, which affects the sense of smell of other animals. This is a similar defense mechanism to an octopus or a squid. The ink is also dependent on the color of the seaweed the sea hare has been feeding on. Their ink can be a variety of colors, such as red or white. They can even deploy a thick cloud of purple ink if the conditions are right.

Fact about the Sea Hare

  • Sea hares present different colors depending on their environment and food source.
  • They use highly toxic ink to deter any potential predators.
  • Sea hares are declared as common on the IUCN’s conservation list.
  • They are considered a delicacy in various cultures around the world.


Are sea hares poisonous?

Yes. Sea hares have a defense mechanism that allows them to ward off potential predators with a toxic ink cloud. They also have a similar toxin in their skin.

Why is it called a sea hare?

The sea hare has two rhinophores, or spouts, similar to sea slugs, sea snails, or even a conventional snail. However, these spouts have been likened to the long ears of a hare. Hence the name sea hare.

Can you have a sea hare as a pet?

In order to house a sea hare in your own aquarium ecosystem, you would have to be an expert aquarist. This is due to the incredibly toxic ink that a sea hare can expel when under threat. If this was to happen, the other animals in your home aquarium could die.

About Ocean Info

At Ocean Info, we dive deep into ocean-related topics such as sealife, exploration of the sea, rivers, areas of geographical importance, sailing, and more.

We achieve this by having the best team create content - this ranges from marine experts, trained scuba divers, marine-related enthusiasts, and more.

Sea Anemone with Clownfish

Dive into more, the ocean is more than just a surface view

Bottlenose dolphins are known to help stranded humans back to the shore

8 of the Most Intelligent Marine Animals

From dolphins' awe-inspiring communication skills to orcas' social complexity, the ocean is home to some of the most intelligent marine animals.

Share to...