Virgulariidae Family of Slender Sea Pens
One Slender Sea Pen of the Virgulariidae Family can be found in this website:
Elongate Sea Pen, Stylatula elongata. A representative of the Virgulariidae Family of Slender Sea Pens.
Phylogeny: Slender Sea Pens are octocorals of the Virgulariidae Family, and like hydroids, jellyfish and sea anemones are in the Phylum Cnidaria. They are the subphylum Anthozoa, the class Octocorallia, the order Scleralcyonacea, and the superfamily Pennatuloidea. The Virgulariidae family is one of sixteen families in this superfamily. The Virgulariidae family contains seven genera and forty-seven species. The name Virgulariidae comes from the Latin word for “small rod”, “twig”, or “slender stick”. This refers to the slender, rod-like, structure of these sea pens. Their common name Sea Pen refers to their resemblance to the quill pens of antiquity. Sea Pens have been known since the ancient Romans, who called them “penna marina” (sea feather or sea pen) and also “mentula alata” (winged penis).
Morphology: Slender Sea Pen colonies display polymorphism characterized by distinct polyp types that are specialized for feeding, water flow, and structural support. The primary feeding polyps (autozooids) have radial symmetry, a hollow digestive cavity, and specialized stinging structures in tentacles surrounding the mouth. Autozooid polyps have a flower-like appearance. Their 8 tentacles are pinnate (having a feather-like appearance). The siphonozooids are dedicated to pumping water through the colony to aid respiration and nutrient distribution. Siphonozooids lack tentacles, or have reduced tentacles. Most species in this family lack mesozooids (intermediate supportive polyps). Octocorals lack the hard calcium carbonate skeletons of stony corals. In place of a hard skeleton, they have tiny spine-like hard parts in their bodies called sclerites (or spicules) that give them some degree of support. Slender Sea Pen colonies are erect and have an elongated shape with bilateral symmetry and a pronounced quill. Their polyp leaves (lateral plumes) are often translucent. They anchor to the substrate by use of peduncle, which is a bulbous extension of the oozoid (primary polyp) that facilitates burrowing and stability. Slender Sea Pens can produce bioluminescence, emitting green light, when disturbed. The longest species in the family can exceed 30 cm (11.8 inches) in length.
Habitat and Distribution: Slender Sea Pens are found on sand and mud substrates. They live in the intertidal zone, and at depths up to 1,200 m (3,936 feet). They avoid high energy areas where water movement can pull them from the substrate. They are found worldwide in polar to tropical seas. At least three species from this family are found in Mexican waters.
Reproduction: Slender Sea Pen colonies are gonochoric (male or female for life). They reproduce sexually, through broadcast spawning, with external fertilization. The eggs develop into planular larvae before they settle to the substrate and metamorphose into their adult form. They may also reproduce asexually, by budding. Some species have life spans that exceed 100 years.
Ecosystem Roles: Slender Sea Pens are suspension feeders that use their tentacles to capture suspended plankton from the surrounding water. In turn they are preyed upon by nudibranchs, fish, and sea stars. Some species can retract into the sediment to avoid predators or strong currents.