Wedge Sea Hare

Care

The Wedge Sea Hare is common amongst seaweeds and grass flats in shallow water environments, especially sheltered bays and lagoons. These fascinating creatures are nocturnal by nature and during the day may be found sheltering under rocks, and by night, actively crawling around seagrass beds in an enthusiastic search for food, mainly various tender macroalgaes. The Wedge Sea Hare is not really suitable for the average marine aquarium on account of its specialist requirements; indeed, if you have your heart set on one of these bizarre, peaceful creatures, the tank must really be planned in advance and set up around its needs if it is to flourish. There are far too many accounts of Sea Hares being used as convenient cleaning machines then returned to the place of purchase, or starving to death when placed in inappropriate conditions. Firstly, the aquarium must be mature and very, very spacious. Not only does the Wedge Sea Hare attain a large size, but it consumes substantial amounts of greenfoods that would be depleted far too quickly in the average sized tank. Secondly, the aquarium should be aquascaped as a shallow, quiet lagoon with bright lighting to encourage the growth of macroalgae upon which the Wedge Sea Hare will spend a large proportion of its time grazing (see Feeding section below for more information). Include plenty of live rock, creating shady crevices/overhangs (large enough for the Sea Hare to take shelter in during the day), and also a reasonable open expanse of fairly deep sand. Thirdly, these gentle creatures do not handle current very well, so they require a calm environment, which may not suit certain corals and fish, so research tankmates carefully. And fourthly, Sea Hares not only consume vast amounts of food, but, in turn, they also excrete a LOT of waste, so you will need to ensure that the filtration system can cope with this copious output, and employ a regular maintenance regime to siphon out what you can. Sea Hares are often nicknamed "Sea Poos" by aquarists for this very reason! Corals should not be harmed, but they may not all enjoy the specialist conditions of the Sea Hare tank; additionally, bear in mind that large Sea Hares can be rather clumsy when searching for food and any corals that are not well-secured to the base rock may be knocked over. Cleaner Shrimps are best avoided as tankmates as they have been known to pick at the appendages and orifices of Sea Hares causing them much distress, and in some cases, premature mortality. Ideal tankmates are small, docile fish which do not share the same food source. Sea Hares are so-named because of their vegetarian diet and the two fringes on the head that look like rabbit ears, especially noticeable when they lift the front of their body up whilst stretching - this resembles a rabbit or hare sitting up on its haunches with ears erect. D. auricularia is the sole representative of the genus Dolabella. These animals have a somewhat different shape to those in the more commonly seen Aplysia genus. D. auricularia is a bulky Sea Hare that is notable for its truncated, sloping, flattened posterior (hence the common name Wedge Sea Hare). The body colour and pattern is variable, but generally it is of shades of brown and green with a covering of papillae, which give it a shaggy appearance that lends it great camouflage in seagrass beds. The posterior of the animal is much wider than the anterior, and underneath all the tissue at the posterior end is a large, flattened, heavily calcified shell. The midsection houses the inhalant siphon (which draws water in to the mantle cavity) and the posterior, the exhalant siphon. When harassed or distressed, the Wedge Sea Hare may give off a cloud of reddish-purple ink, which is released from the ink gland in the mantle, directly over the ctenidium (gill), with the ink being released through pores on the ventral surface of the gland. This ink is thought to be derived from red algae that the Sea Hare consumes. They also produce a mildly noxious substance that is secreted from the opaline glands, which are located beneath the floor of the mantle cavity. This viscous substance is secreted in much smaller quantities than the ink, and is not dependent upon red algae being eaten. These secretions can pose a problem in the confines of the home aquarium. When kept in ideal conditions without fear of harassment, your Sea Hare is unlikely to ink. However, if something is not to its liking or if it is disturbed by tankmates (or even accidentally by yourself when carrying out maintenance in the aquarium) and it does emit a cloud of ink, you will need to take swift action. The toxins can adversely affect other animals in the aquarium, so if this does happen, immediately siphon out as much of the concentrated cloud of ink as you can before it disperses too much, then without delay, run a high powered filter full of activated carbon to absorb the noxious substances. Keep changing the carbon regularly as when saturated with toxins, it will begin to release them back into the water. Ideally, change the carbon several times to ensure that all toxins have been removed from the water, and top the tank back up with clean water. Hopefully this scenario will not occur, but it is worth having a few essential pieces of equipment on stand-by in close proximity to the tank, just in case of an emergency. Likewise, when acclimatising one of these creatures to the aquarium, great care must be taken so that it does not become stressed. Drip acclimatisation over the course of an hour or two is suggested for best results. Be aware that Wedge Sea Hares can climb up the glass and escape from open topped aquaria, so tanks with tight fitting coverslides are recommended. As these animals are most active during the evening and night, it would be beneficial to use some form of blue moon lighting to observe their nocturnal antics for an hour or two each evening after the main illumination switches off. May also be seen on sale as the Dolabella Sea Hare, Eared Sea Hare, Blunt-End Sea Hare, and sometimes even labelled with the misnomer 'Giant Sea Hare' (a name usually reserved for the truly enormous, black species Aplysia vaccaria). Advanced aquarists only.

Feeding

Requires macroalgae, and lots of it, on an ongoing basis. A refugium or separate aquarium could be used to culture various macroalgaes on pieces of rock, and the rocks rotated with those in the main tank on a regular basis, to help provide continual nourishment. In nature these sea hares have been observed feeding on green, brown, and red macroalgae, and a mixed diet is preferable to that of a single species of algae. It will not consume calcareous algae, and most specimens do not touch Caulerpa. Some will eat sheets of dried algae/seaweeds (many aquarists find cutting the sheets are into long strips before adding to the tank gives the best results). A mature aquarium is absolutely essential.

Breeding

This species has not been bred in the home aquarium. Wedge Sea Hares are hermaphrodites with both male and female reproductive organs. Any individual sea hare can act as either a male or female, or simultaneously as both. However, they do not self-fertilise. In the wild, when ready to breed, these creatures exhibit some truly fascinating behaviour, congregating in lines to form 'mating chains'. The individual at the front of the line acts as the female, receiving sperm from the second individual attached behind (the penis is located on the head). Then the third individual fertilises the second individual with sperm and so on, to the end of the chain, where the last one acts as a male only. All sea hares in the middle of the chain are both male and female, passing and receiving sperm. The individuals at the front and back of the chain then sometimes join up to form a full 'mating circle'. Fertilisation is internal, and up to 80 million jelly-encased yellow eggs are laid in long spaghetti-like strings amongst eelgrass, that can form a mass several inches in diameter. The eggs turn brown within 8-9 days and typically hatch around 10-12 days. The free-swimming larvae are planktonic and take approximately 30 days to settle (usually on red algae). Development progresses from a trochophore larval stage to a veliger larval stage, to a juvenile stage, before the final adult stage, all of which takes around 3 months to complete.