Onchidella
Onchidella is a genus of air-breathing sea slugs, known as side-gilled slugs, in the family Onchidiidae. They are small, soft-bodied mollusks that are found in intertidal and supratidal zones along coastlines worldwide. Onchidella species are characterized by their flattened, oval or elongated bodies, typically less than 2 cm in length, and a prominent, mantle-like fold that runs along the back. They have a pair of retractable tentacles on their heads and two pairs of cephalic sensory organs called rhinophores.
Common Names
Members of the genus Onchidella are often referred to as "side-gilled slugs" or "sea slugs".
Characteristics
Onchidella species exhibit several distinguishing features:
- Body shape: Flattened, oval or elongated, with a mantle-like fold along the back.
- Size: Typically less than 2 cm in length.
- Coloration: Varies widely depending on species and habitat, ranging from gray and brown to black and even bright shades of orange or yellow.
- Respiratory system: Breathe air through a pair of gill openings located on the sides of the body, hence the name "side-gilled slugs".
- Feeding: Feed on algae, fungi, and decaying organic matter.
- Reproduction: Hermaphroditic, capable of self-fertilization.
Environment
Onchidella species are found in intertidal and supratidal zones, particularly in areas with abundant algae and decaying organic matter. They are often encountered on rocks, seawalls, and in tide pools. These slugs are well adapted to survive in environments that are exposed to air during low tide, as they can retain moisture and breathe through their gills.