Black Seahare

The black sea hare can grow to be very large; the longest recorded specimen measured 99 cm (39 in) when crawling (thus fully extended), and weighed nearly 14 kg (31 lb).

Unlike Aplysia californica, the body of this species is relatively firm, and the parapodia are joined behind the siphon.

Unlike many other members of the same family and genus, this species is incapable of producing ink.

This sea hare species lives in the northeast Pacific Ocean off California, United States, and Baja California, Mexico, including the Gulf of California.

All Aplysia species are herbivorous. This species eats brown seaweeds and kelp, which give the animal its typically very dark coloration.

Aplysia vaccaria has a lifecycle of one year. They grow very quickly, at an average rate of 4.9 g/day. This high rate of growth allows A. vaccaria to become the largest known species of sea slug. It is a herbivore that feeds on brown algae, but its close relative A. californica feeds almost exclusively on red algae. This difference in food sources likely minimizes competition between the two species, which share much of the same habitat. A. vaccaria is found in the intertidal and upper-subtidal zone, meaning that it can survive exposure to air while the tide is out. It is rarely preyed upon by other organisms, which has made it the subject of various experiments testing for a secreted biotoxin that discourages predation. The large size of A. vaccaria also contributes to its lack of predators. It is simply too big for many predators to attack or consume.

Aplysia vaccaria is a simultaneous hermaphrodite; it has both male and female sex organs that are able to contribute to sexual reproduction at the same time, which is distinct from nonsimultaneous (or sequential) hermaphrodites, which only have one sex organ present or functional at any one time. Being simultaneously hermaphroditic is advantageous because any two individuals are able to reproduce with one another, which facilitates them finding mates. Despite having both sex organs functional during reproduction, only one Aplysia vaccaria acts as a sperm donor during the mating encounter, which is determined by the relative sizes of the two individuals. The smaller individual most often acts as the sperm donor, while the larger individual acts as the sperm recipient. Because the reproductive role of A.