Eunice aphroditois is a giant marine worm in the speciose polychaete family Eunicidae (which contains over 300 species names; Zanol et al. 2010; Fauchald 1992). One of the world’s longest worms, E. aphroditois is a dramatic sight with different accounts measuring individuals 3-6 meters (10-20 feet) long, their bodies up to 25 mm (1 inch) across.These omnivorous, opportunistic, free-living worms live head-up in burrows just under sand or gravel sediments or in boulders/coral rubble. Five tentacles around their mouth, characteristic of the genus, extend in the water. When it detects prey, the worm springs from its lair, everting its proboscis to expose a fierce pair of mandibles, with which it pulls the prey into its hole.(Video here: https://www.youtube.com/watch?v=GAgWm3G44Aw&feature=player_embedded)
In the 1990s, a giant eunicid worm from the Indo-pacific was photographed and its astonishing feeding behavior documented (as Eunice sp., as even experts could not identify it to species) in an identification manual, Coral Reef Animals of the Indo-Pacific (Gosliner et al. 1996): “...with its 5 pairs of massive, spring loaded jaws, [this species] appears like a frightening apparition from a science fiction movie… This species is a voracious predator.It was observed to feed on a file fish of more than 150 mm in length.When the file fish ventured too close to the worm it emerged slightly from its burrow and seized the fish in its jaws with lightning speed.In an instant, the worm had pulled the fish beneath the sand surface and begun to consume it.”
Originally described from tropical Indo-Pacific waters around Sri Lanka (Pallas 1788), this species is reported around the world, although experts believe this name confounds a multitude of similar-looking giant eunicid worm species.For example, recent work formally distinguished the giant eunicid worm (and commercially important fishing bait species) that inhabits the Mediterranean and Agean Seas as E. roussaei rather than E. aphroditois (Zanol and Bettoso 2006).The difficulties of teasing apart the different species morphologically has made taxonomy, systematics and understanding of the distribution and ecology of species within the genus Eunice very complex. In combination with further study of type material and more collection at type locations, molecular bar coding and molecular phylogenetic characters may prove a helpful tool in the much needed task of defining this and other giant eunicid species more precisely (Schulze 2011; Salazar-Vallejo et al. 2011; Zanol et al 2010).
Gosliner et al. (1996) coined the name Bobbit worm for the Eunice sp. illustrated in their book, associating the worm to the at the time widely-discussed Lorena Bobbit court case.The name simply refers to the sharpness of the worm’s mandibles slicing its prey under attack and the resemblance of the worm to a phallus when holding itself erect to catch prey, not to imply that this worm castrates its mate - which it doesn’t as these worms are broadcast spawners - however this misinterpretation has circulated especially on the web. Just as most giant eunicid worms around the world are ascribed to the species name Eunice aphroditois, most of these worms are also referred to as the Bobbit worm, so rather than as a common name for E. aphroditois, “Bobbit worm” would be better applied generally to all giant eunicid worms (Mah 2013), although these giant worms are not necessarily a monophyletic grouping.
Early on in the taxonomic history of the eunicid worms, several specimens from around the world were synonymized into one species name (E. aphroditois).This had the effect of assuming that certain characters had a large amount of variation in the species (e.g. antennal size, articulation of the antennae, type of pectinate chaetae type, maxillae teeth number (Salazar-Vallejo et al. 2011). Thus even though, for example, specimens in Australia had very different branchial patterns and gut contents from those in the Phillipines, they were regarded as the same species.
Salazar-Vallejo et al. 2011 believe that giant eunicid worms photographed from distinct geographies show morphological and behavioral differences that have not as yet been sufficiently analyzed, and historical lumping of these taxa may hide taxonomic diversity.To fully resolve these taxonomic issues requires more understanding of variation (especially of diagnostic characters) in different populations.Because type specimens have been lost over time, and because it is difficult to extract genetic information from embalmed organisms, Salazar-Vallejo et al. 2011) call for resampling at type localities, and using molecular and morphological methods in tandem to characterize possible hidden diversity.These authors identify the following taxa as in particular need of attention: Eunice aphroditois (Sri Lanka), E. gigantea (La Reunion), E. kinbergi (Cape Town), E. longisetis (Bermuda), E. macrobranchia (Cape Town), E. maxima (Naples), E. nigricans (Jamaica), E. purpurea (Adriatic Sea), E. roussaei (Bay of Biscay), E. violacea (Pacific Costa Rica), and E. violaceomaculata (Florida), E. djiboutensis Gravier, 1900 and E. mutabilis Gravier, 1900 (Red Sea).
Some of the variation photographed includes:
Worms from the Phillipines and Indonesia: Dark bands on body; Median antenna same length as peristomal width; Banded anterior appendages; Fusiform peristomal cirri; Branchiae start by chaetiger 5; No white coloration on any anterior chaetigers
Worms from Australia: Body and appendages red in color; Median antennae 2-3 times the width of the peristome; Chaetiger 4 is white; Unknown as to which chaetiger is the start of branchiae.
A worm similar to E. torquata: Body solid red in color; Chaetiger 4 is pure white; Antennae are banded; median antennae 2-3 times the width of the peristome; Peristomal cirri are cirriform and whte; Branchiae start by chaetiger 3, pectinate by chaetiger 9.
Bengal eunicid (Indonesia): Gold and purple body coloring, with lines between segments and longitudinal along body; Chaetiger 4 is white; Solid gold-colored antennae, laterals just longer than the width of the peristome; Peristomial cirri are dark; Branchiae start by chaetiger 7.
Singapore eunicid: dark grey body, with spots mid-body; Chaetigers 4 and 5 have pale bands; Antennae, palps and cirri are pale, with dark tips; Branchiae start by chaetiger 7.
Caribbean eunicid (first form): Dark purple body with fine longitudinal lines; Banded appendages; Peristomal cirri are cirriform, banded; Pectinate branchiae, start at chaetiger 7.
Caribbean eunicid (2nd form): Body dark red with subtle banding on anterior appendages; peristomal cirri are cirriform; Pectinate branchiae, start at chaetiger 9; Younger individuals (and regenerated parts of older individuals) are purple.
Mediterranean Sea species (Eunice gigantea)
Pacific Coast of Central America (E. violacea)
Bay of Biscay/Mediterranean (E. roussaei)
Caribbean (E. violaceomaculata)
(Salazar-Vallejo et al. 2011)
Eunice aphroditois is a benthic bristle worm of warm marine waters. It lives mainly in the Atlantic Ocean, but can also be found in the Indo-Pacific.[1][2] It ranges in length from less than 10 cm (4 in) to 3 m (10 ft).[3] Its iridescent cuticle produces a wide range of colors, from black to purple. This species is an ambush-predator; it hunts by burrowing its whole body in soft sediment on the ocean floor and waiting until its antennae detect prey.[4] It then strikes with its sharp mouthparts.[5] It may also be found among coral reefs.
Eunice aphroditois is commonly known as the sand-striker or bobbit-worm;[6][7][8][9] the latter name is from the John and Lorena Bobbitt case.[10]
These ambush predators have no eyes and five antennae on their head that are used to sense prey.[11] The body is covered by a hard exoskeleton.[12] The mandibles can be retracted inside the body and are responsible for striking and stunning prey; they are capable of snapping some prey in half.[13] Typically, E. aphroditois ranges from deep purple to black, along with metallic colors. The largest known specimen on record reached 299 centimeters (9.81 ft) in length,[3] making it the longest known member of the polychaete class. Despite these great lengths, the worms are slim, with the body only about 25.5 millimeters (1.00 in) wide.
This species may be found prowling among the prey-rich environment of coral reefs, where its coloration allows it to blend in and its slim body enables it to hunt in tight places.[13] It inhabits a wide range of other habitats,[14] particularly sandy and muddy sediments, as well as around rocks and sponges.[13] It has been recorded at depths of up to 95 meters.[7]
E. aphroditois senses passing prey with its antennae, seizes the prey with its mouth, and drags it into its burrow. To reduce predation risk, some fish engage in mobbing behavior, during which a group of fish will direct jets of water into the worm's burrow to disorient it.[4] This species is not only considered to be a carnivore, feeding on a plethora of species of fish, but it can also be considered an herbivore/omnivore, feeding on algae, as well as a decomposer, feeding on dead and decaying matter.[15]
Ancestral species may have exhibited the same hunting-behavior twenty million years ago, according to fossil-records.[16]
Like most of the class Polychaeta,[17] E. aphroditois is a sexually-reproducing organism that lacks external reproductive organs. During spawning, female polychaetes produce a pheromone that attracts males and causes them to release sperm; this in turn triggers the female to release eggs into the water, where fertilization occurs.[7] Few offspring survive to adulthood because often, the eggs are eaten by other animals or destroyed.
The lifespan of E. aphroditois is believed to be three to five years.[18]
Like many species of bristle worm, E. aphroditois can also reproduce asexually by splitting into multiple segments, then regenerating body parts such as the head or tail. This enables them to survive being attacked by predators.[19]
While not commonly kept in aquaculture, individuals of E. aphroditois are occasionally found in home aquaria, where smaller specimens can evade detection by being transported into the tank in live rocks, where they then grow in size.[20] As E. aphroditois hunts fish, it cannot be kept as part of a community tank and should be removed when found, as it will deplete the aquarium's stock by direct predation.[21]
E. aphroditois can be difficult to remove from aquariums due to their abilities to split into new individuals when handled,[19] dig holes into rocks, and curl up and hide in small rocks despite their length.[22]
Eunice aphroditois is a benthic bristle worm of warm marine waters. It lives mainly in the Atlantic Ocean, but can also be found in the Indo-Pacific. It ranges in length from less than 10 cm (4 in) to 3 m (10 ft). Its iridescent cuticle produces a wide range of colors, from black to purple. This species is an ambush-predator; it hunts by burrowing its whole body in soft sediment on the ocean floor and waiting until its antennae detect prey. It then strikes with its sharp mouthparts. It may also be found among coral reefs.
Eunice aphroditois is commonly known as the sand-striker or bobbit-worm; the latter name is from the John and Lorena Bobbitt case.
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