Slipper lobster

Slipper lobsters make up the family Scyllaridae, a group of roughly 90 species of achelate crustaceans within the decapod clade Reptantia. They inhabit warm oceans and seas worldwide. Despite their name, they are not true lobsters; their closest relatives are spiny lobsters and furry lobsters. Their most distinctive feature is the pair of enlarged antennae that extend forward from the head as broad, flattened plates. Every species of slipper lobster is edible, and several—such as the Moreton Bay bug and the Balmain bug (Ibacus peronii)—are commercially valuable.

**Description** The head of a slipper lobster has six segments, and the thorax has eight, all covered by a thick carapace. The abdomen consists of six segments, each bearing a pair of pleopods. The thoracic appendages function either as walking legs or as maxillipeds. The head segments carry various mouthparts and two pairs of antennae. The first pair, or antennules, are mounted on long, flexible stalks and are used to sense the environment. The second pair are the animal’s most striking feature: they are expanded and flattened into large plates that project horizontally forward. Slipper lobsters vary greatly in size. The smallest species, the Mediterranean *Scyllarus pygmaeus*, reaches a maximum total length of 55 millimeters (2.2 inches) and is rarely longer than 40 mm (1.6 inches). The largest, *Scyllarides haanii*, can grow up to 50 centimeters (20 inches) long.

**Ecology** Slipper lobsters are typically bottom-dwellers on continental shelves, living at depths of up to 500 meters (1,600 feet). Their diet includes a range of mollusks—such as limpets, mussels, and oysters—as well as crustaceans, polychaetes, and echinoderms. They grow slowly and can live to a considerable age. Unlike other decapod crustaceans, they lack the giant neurons needed for tail-flipping escapes. Instead, they rely on burying themselves in the substrate and their heavily armored exoskeleton to avoid predators. The main predators of slipper lobsters are bony fish; in the Mediterranean, the grey triggerfish is the most significant predator of *Scyllarides latus*.

**Life cycle** After hatching from eggs, young slipper lobsters go through about ten instars as phyllosoma larvae—leaf-like, planktonic zoeae. These stages last most of a year, after which the larva molts into a "nisto" stage that persists for a few weeks. Little is known about the transition from this stage to adulthood, after which the lobsters continue growing through a series of molts.

**Commercial importance** Slipper lobsters are fished wherever they occur, but they have not been targeted as intensely as spiny lobsters or true lobsters. Fishing methods depend on the species’ habitat. Those that prefer soft substrates, such as *Thenus* and *Ibacus*, are often caught by trawling. Those that favor crevices, caves, and reefs—including *Scyllarides*, *Arctides*, and *Parribacus* species—are usually collected by scuba divers. In 1991, the global catch of slipper lobsters was reported at 2,100 tonnes. More recently, annual production has been around 5,000 tonnes, with the majority coming from *Thenus orientalis* in Asia.

**Common names** The family Scyllaridae is known by several common names. The most widespread is "slipper lobster," followed by "shovel-nosed lobster" and "locust lobster." "Spanish lobster" refers to members of the genus *Arctides*, "mitten lobster" to *Parribacus*, and "fan lobster" to *Evibacus* and *Ibacus*. In Australia, many species are called "bugs"—for example, the Balmain bug (*Ibacus peronii*) and the Moreton Bay bug (*Thenus orientalis*). Other Australian names include "bay lobster," "blind lobster," "flapjack," "flat lobster," "flying saucer," "gulf lobster," "mudbug," "sandbug," "shovel-nose bug," "shovelnose lobster," "crayfish," "slipper bug," and "squagga." Less common terms are "flathead lobster" (for *Thenus orientalis*) and "bulldozer lobster." In Greece, they are sometimes called *Kolochtypes*, which roughly translates to "bum hitter." Twenty-two genera are recognized, most of which were established in 2002 by Lipke Holthuis for species previously placed under *Scyllarus*.

**Genera** Slipper lobsters belong to the following genera.

**Gallery** A gallery of various slipper lobster species is included.

**Fossil record** The fossil record of slipper lobsters extends back 100–120 million years, which is considerably shorter than that of their closest relatives, the spiny lobsters. An important earlier fossil is *Cancrinos claviger*, described from Upper Jurassic sediments at least 142 million years old. This species may represent either an ancestor of modern slipper lobsters or the sister group to the family Scyllaridae sensu stricto.