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Species Spotlight: Sea Hare

This species spotlight is all about the sea hare! These fascinating creatures are a gastropod of the family Aplysiidae and have small internal shells rather than an external shell.

PC: Getty Images

Sea hares usually are between 3 and 14 inches and can camouflage their patterns and colors by eating different types of foods. Some sea hares may have additional defense mechanisms from ingesting toxic algae. This toxicity can allow a sea hare that feels threatened to release a dye that is commonly purple. This dye gives sea hares added time to escape, as it confuses the predator and masks the sea hare’s location. Some sea hares also have a toxic slime that further protects them. (Australian Geographic)

PC: Genny Anderson

Sea hares get their name because of the “ears'' on top of their head that look like the tall ears of a land hare. These protruding “ears'' are very purposeful, as they are really tentacle-like organs called rhinophores. These tentacles are specialized sensory organs that aid their olfactory (smell) and tactile senses by detecting chemicals in the ocean (discoverwildlife). The name originated from the Ancient Greek Word “rhino,” meaning nose, and “phore,” meaning carrier. It encapsulates the general function of the organ, as it serves as the “nose” that detects the smell and touch (seaslugforum).

PC: Chad King/NOAA PC: Sarah Darnell

Do you see the resemblance?

Scientists have studied rhinophores for decades to obtain insights about human memory and learning. While their nervous system is much simpler compared to that of humans, its simplicity has made the sea hares the ideal candidate for neurological research.

For years, scientists and researchers have dedicated their life to understanding the fundamental essence of memory. While the answer to such a question remains unresolved, most researchers are divided between the two hypotheses: bioelectrical and synapses. The study of sea hares supports the idea that memory works with synapses. The synapses approach states that connections between the cells and learning levels are positively correlated. In other words, the stronger the connection, the more that a brain is learning (seaharerevealssecrets).

In 2000, Dr. Eric Kandel won the Nobel Prize in Physiology or Medicine with his work on sea hares and memory. For decades, Kandel spent his time researching both long-term and short-term memory at the molecular level. According to Kandel, memory can be divided into two different sectors: explicit memory storage, which accesses the complex functions, and implicit memory storage, which accesses simpler tasks (withthehelpofseahares).

Dr. Eric Kandel; PC: APA/Georg Hochmuth

Kandel dedicated his life to studying explicit memory storage, which involves the hippocampus. To comprehend the most complex part of the body, Kandel chose an animal with the simplest structure: the sea hare. In 2000, Kandel’s work was awarded the Nobel Prize for discovering the different changes in nerve cell connections in both short-term and long term memories. He concluded that the changes in nerve cell connections are temporary in short-term memory and permanent with long term memory. He is famously quoted for his statement, “If you remember anything about this conversation, you will have a different brain than you started out with before the conversation.” The sea hare is thought to also hold answers surrounding fixing and aiding memory in old age. They truly are incredible creatures that have greatly influenced the very ways we view and understand our own minds (seahares&ourbrain).

If you enjoyed this species spotlight, be sure to check out some others on our blog, including: Opaleye, Northern Elephant Seal, Sea Urchins, Vaquita, and Abalone. Additionally, if you want the opportunity to potentially see a sea hare in person, be sure and sign up here for OC Habitat’s guided hike through a Marine Protected Area in May or June. They have been spotted on this hike before, but remember not to touch them! If you would like more information on tidepool species, check out OCH’s Tidepools Guide.

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