Arminidae Family of Nudibranchs

One Nudibranch of the Arminidae Family can be found in this website:

Striped Nudibranch, Armina californica. A representative of the Arminidae Family of Nudibranchs.

Phylogeny:   Arminidae Nudibranchs of the Arminidae Family are in the phylum Mollusca. They are in the class Gastropoda and the subclass Heterobranchia of different gilled slugs. They are in the order Nudibranchia and the suborder Arminina. The superfamily Arminoidea is one of two superfamilies in this suborder. The Arminidae Family is the only family in the superfamily Arminoidea. The Arminidae Family consists of six genera and around ninety-eight species. The name Arminidae comes from the Old German word for “warrior” or “soldier”. Species in this family are also commonly called Arminids.

Morphology:  Arminid Nudibranchs have an elongated oval outline and a flattened profile. Their soft bodies lose their shells during their larval phase. The body tapers gradually to a pointed or rounded tail. They have a thick mantle that usually has lengthwise ridges, but may instead have irregular pustules, papillae, or be smooth. Arminids lack external gills.  Their dorsal surfaces do not have cerrata. Arminids have numerous cnidosacs (sacks containing stinging cells) around the margins of their mantles. Their oral veils are distinguished by having short tentacular lobes laterally.  Like all nudibranchs they have rhinophores (horn-like projections) on their heads that are chemosensory organs that help them to locate food and potential mates. Arminid rhinophores are set well forward and close together. The rhinophores have clubs with compact vertical lamellae. Nudibranchs lack complex eyes, but have photo-receptors that sense light and dark. Some species in this family are brightly colored. Arminids reach a maximum of 20 cm (7.9 inches) in length but most are much smaller.

Habitat and Distribution:  Arminid Nudibranchs are found on, and within, sand and mud substates. The live in the intertidal zone and at depths up to 200 m (660 feet). They are found worldwide in tropical to temperate seas. Four species from the Arminidae Family are found in Mexican waters.

Reproduction: Arminid Nudibranchs are simultaneous hermaphrodites. They reproduce sexually by hypodermic insemination. This occurs when both mating partners dart their penis toward each other to induce one to act as a male and the other as the female. The victorious one to penetrate the body wall is the dominant male. The eggs are laid as a mass on sponges or on the bottom substrate. The eggs hatch into veliger larva and later metamorphose into adults.

Ecosystem Roles:  Arminid Nudibranchs feed on soft coral, sea anemones, sea pens, and sea pansies. They have the ability to store toxins from their prey in their mantle that provides them with a defense against predation. They are prey for crabs, fish, and other sea slugs.