Valanciniidae Family of Ribbon Worms

One Ribbon Worm of the Valanciniidae Family can be found in this website:

Zebra Worm, Baseodiscus mexicanus. A representative of the Valanciniidae Family of Ribbon Worms.

Ribbon Worms are members of the Valenciniidae Family (recently reclassified from the the Valenciniidae Family) and are also known as Bootlace Worms or Proboscis Worms, are in the Phylum Nemertea which includes the unsegmented worms. They all have bilateral symmetry and have are coelmate having an interior body cavity that is completed line by a peritoneum. They are found in freshwater, marine and terrestrial environments. Ribbon Worms are in the Class Anopla and are characterized by having an unarmed proboscis, a mouth located posterior to the cerebral ganglia (brain), and a central nervous system that is located within the body wall. They are of the Order Heteronemertea in that that their body wall has three layers of muscles, an outer longitudinal layer, a middle circular layer, and an inner longitudinal layer and a nervous system that lies between the middle and outer layers. Members of the Valenciniidae Family all have a proboscis that consists of an outer longitudinal muscle layer and an inner circular layer.

The Valenciniidae Ribbon Worms are found in marine environments and are some of the most highly visible very colorful worm species in the sea and can approach 30 m (8 feet) in length. Most species in the Valencinidae Family have the ability to contract and expand their bodies dramatically. They have a complete gut with a mouth and an anus and a true circulatory system. Ribbon Worms may be parasites, predators, or scavengers.

Most predatory Ribbon Worms are nocturnal consume annelid worms, bivalves, small crustaceans and fish, that move along the ocean floor assisted by slime and cilia. They capture prey by utilizing a long muscular sticky, slime covered proboscis that lies in an interior cavity called the rhynchocoel which can be quickly opened and inverted like a wind-blow umbrella. The slime contains neurotoxins that incapacitate the prey which also provide them with a defense mechanism against predation. They are preyed upon by shore birds, crabs, fish and other ribbon worms.

Ribbon worms are found worldwide in Polar, Temperate and Tropical seas from the intertidal zone to very deep oceanic canyons. The Valenciniidae Family has approximately four hundred global members of which twenty-three are found along the Pacific Coast of Mexico.