Antennids

Antennids are a proposed lineage of marine invertebrates distinguished by prominent, multi-segmented antennae that extend from the head region and often along the body. The name derives from these appendages, which function as primary sensory organs and assist in foraging in low-visibility environments. In many species, the antennae bear specialized hairs and chemosensory structures, enabling detection of chemical cues in the water column.

Morphology and anatomy emphasize a compact to elongated body plan with a flexible outer covering. The anterior region bears several pairs of long antenniform appendages; some species also possess additional lateral appendages for stabilization and subtle maneuvering. The exoskeleton or cuticle varies among species, ranging from rigid to pliant, with varying degrees of ornamentation that can aid camouflage among substrates.

Ecology and habitat indicate that Antennids occupy shallow coastal and continental-shelf zones in temperate to tropical waters. They are typically detritivores and small scavengers, using the antennae to locate organic matter and microalgae. Some species employ filter-feeding strategies aided by sensory input from the antennae, and a few form loose associations with other invertebrates for shelter or feeding opportunities.

Life cycle and reproduction are sexual, with most species being dioecious and releasing gametes into the water for external fertilization. Larval development includes several planktonic stages before settlement and metamorphosis into juveniles, a cycle that promotes wide dispersal in suitable habitats.

Phylogeny and evolution place Antennids in a distinct clade of marine invertebrates, with antennae representing a key ecological specialization. Ongoing comparative studies seek to clarify their relationships to other sensory-rich invertebrates and to understand the evolutionary pathways that produced their antennae-rich morphology.