见内文
海鹿科（学名：Aplysiidae）是海鹿总科（学名：Aplysioidea，又名海兔超科）之下唯一的一个科。与其它海蛞蝓相比，海鹿的体型相比较大。它们的头小，有着又长又圆的身体，还有长长的一对检嗅器（英语：rhinophore）。这些物种都是一些没有螺壳的“海螺”，一般“海鹿”会用来叫体型相对大很多的物种，而体型较小的会叫作“海兔”，但也有文献不论大小都称呼为“海兔”。在这些物种当中，以加州黑海兔（）的体型最大，也是所有腹足纲物种中体型最大的一种，经常在内容农场的“海怪”文章提及。
Members of the Aplysiidae have an atrophied inner shell (in contrast with the nudibranchs, which have no shell at all). In and , this shell is a soft flattened plate over the visceral rear end, where it is fully or partially enclosed in the mantle skin. In , the shell is ear-shaped. The shell is only present in the larval stage of the two genera and , and on this basis they have been grouped into the subfamily Dolabriferinae.
They are rather large animals. Their length can reach up to 75 cm (), and they can weigh well over 2 kg. They are cosmopolitan and found in temperate and tropical seas, inhabiting shallow coastal areas and sheltered bays, thick with vegetation.
The Aplysiidae are herbivorous, eating a variety of red, green or brown algae and eelgrass. Their color is diet-derived from the pigments of the algae. They concentrate the toxins found on algae.
Some species spout ink when disturbed or attacked, and they may also swim (rather than crawl) away, using their broad wing-like flaps or parapodia. The ink is extracted from their algal food, rather than being synthesized.
Sea hares have two main secretory glands in their mantle cavity.
The genus has proved useful as a model in neurobiology for the study of electrical synapses, which mediate the release of the clouds of ink.
Sea hares are hermaphrodites, with fully functional male and female reproductive organs. The penis is on the right side of the head while the vagina is situated in the mantle cavity, beneath the shell, deep down between the parapodia. It is therefore physically impossible for mating partners to act as both male and female at the same time.
They have unusual mating habits: they can mate in pairs with one acting as a male, the other as a female, but they commonly occur in quite crowded numbers during the mating season, and this often leads to chains of three or more sea hares mating together. The one at the front acts as a female and the one at the back as a male. The animal(s) in between are acting as both males and females, in other words, the animal receiving sperm passes its own sperm to a third sea hare.
海鹿科的捕食者包括有海蜘蛛、隆头鱼科物种及海龟。
2004年的一份研究文献显示海鹿科是一个单系群，由两个支序组成：
The authority of this family is still somewhat in dispute. The family was incorrectly originally spelled as Laplysiana. This was a Latinized form of the original common name "les Laplysiens" as described in , 1:320 by Lamarck in 1809. Rafinesque introduced the new name Laplysinia in 1815. In 2001 Bouchet & Rocroi advocated the attribution of the name Aplysiidae to Lamarck.
Classification after N. B. Eales (1984):
