Valenciniidae Family of Ribbon Worms
One Ribbon Worm of the Valenciniidae Family can be found in this website:
Zebra Worm, Baseodiscus mexicanus. A representative of the Valenciniidae Family of Ribbon Worms.
Phylogeny: Ribbon Worms of the Valenciniidae Family are unsegmented worms in the phylum Nemertea. Ribbon Worms are in the class Pilidiophora and the order Heteronemertea. The Valenciniidae Family is one of three families in this order. The Valenciniidae Family contains three subfamilies, ten genera, and around seventy-two species. Species in this family are also commonly called Bootlace Worms, Proboscis Worms, or Valenciniids. The etymology of the name Valenciniidae is uncertain. Some sources say it was in honor of someone named Valencia. Other sources say it comes from the Latin word for “strong”, “vigorous”, or “powerful”.
Morphology: Valenciniid Ribbon Worms are extremely elongated and dorso-ventrally flattened, giving them a tape-like appearance. They are soft-bodied and bilaterally symmetrical. As Nemerteans they are characterized by an eversible proboscis (tubular organ that can be shot outward by turning inside-out) that is used for feeding. Their body wall has three layers of muscles, an outer longitudinal layer, a middle circular layer, and an inner longitudinal layer. Their nervous system, consisting of a brain and lateral nerve cords, lies between the middle and outer layers. The proboscis is unarmed (lacks a stylet) and consists of an outer longitudinal muscle layer and an inner circular layer. They have a complete gut with a mouth and an anus, and a true circulatory system. Many species in this family have a banded or striped color pattern. Valenciniid Ribbon Worms have the ability to contract and expand their bodies dramatically. Some species exceed 1 m (39 inches) in length.
Habitat and Distribution: Valenciniid Ribbon Worms are found in marine environments. They may be found on, burrowing into, or hiding under, rocks, algae, coral rubble, dead corals, sand, and mud. They range in depth from the intertidal zone to depths exceeding 10,000 m (32,800 feet). Valenciniid Ribbon Worms are found worldwide in polar to tropical seas. There are twenty-four species from the Valenciniidae Family found in Mexican waters.
Reproduction: Valenciniid Ribbon Worms are gonochoric (male or female for life). They reproduce sexually, with external fertilization, which produces larvae that later metamorphose into juvenile Ribbon Worms.
Ecosystem Roles: Valenciniid Ribbon Worms are primarily carnivorous predators and occasional scavengers. Most predatory Ribbon Worms are nocturnal, and consume annelid worms, bivalves, small crustaceans and fish. They capture prey by utilizing a long, muscular, sticky, slime-covered, proboscis. The proboscis lies in an interior cavity called the rhynchocoel which can be quickly opened and inverted like a wind-blown umbrella. The proboscis sticks to, and entangles, the prey. In many species the proboscis slime contains neurotoxins that incapacitate the prey. Neurotoxins also provide them with a defense mechanism against some predators. They are preyed upon by shore birds, crabs, fish and other ribbon worms. Valenciniid Ribbon Worms move along the ocean floor assisted by slime and cilia.