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Aplysiida

life science Maturity 11-13 Next article →

Sea hares are large, soft animals that live in the ocean.

Sea hare DSC01663
Sea hare DSC01663

They belong to a group called Aplysiida. This name comes from Greek words meaning "without a shield." This is because they do not have a hard head shield. Most sea hares have a thin, internal shell made of protein. Some sea hares do not have a shell at all. They are quite large and bulky when they are adults. The biggest kind is called Aplysia vaccaria. It can grow to a very long length and a heavy weight.

Sea hare DSC01663
Sea hare DSC01663

These animals have many clever ways to stay safe. They are herbivores, which means they eat seaweed. Their color often matches the seaweed they eat. This helps them hide from enemies using camouflage. Sea hares have a great sense of smell. They use two long parts on their heads called rhinophores to find scents. If a predator gets too close, the sea hare can release ink. This ink comes from ink glands and looks like smoke. The ink can be red, white, or purple. It can even block the sense of smell of a predator.

Sea hare DSC01663
Sea hare DSC01663

Sea hares move through the water in interesting ways. Some use a method called turbo jet propulsion to swim. Other sea hares have side parts called parapodia. These look like jelly-like wings that flutter. They can move much like a stingray does. Their motion might look a bit random or erratic. This is because they do not have complex brains like a squid. They still reach their goals like the seabed. They use ocean currents and waves to help them move.

Sea hare DSC01663
Sea hare DSC01663

People have known about sea hares since Roman times. Scientists have worked hard to name them correctly over the years. Paul Henri Fischer first described the group Aplysiida. Later, Johannes Thiele named it a suborder in 1925. In 2005, researchers Bouchet and Rocroi used the name Aplysiomorpha. In 2010, Jörger and others moved the group to Euopisthobranchia. Many people around the world also eat sea hares. In Hawaii, they are called kualakai and cooked in an imu. In the Philippines, people eat egg strands called lokot.

Sea hare DSC01663
Sea hare DSC01663

Sea hares are also very important for science. One species is named Aplysia californica. It is famous because it has very large axons. Axons are parts of the body that carry signals. Scientists use these large parts to study how animals learn and remember. A scientist named Eric Kandel won a Nobel Prize for this work. He studied how a sea hare reacts to certain touches. This helps us understand how memory works in living things.

Sea hare DSC01663
Sea hare DSC01663
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