Benthimermis		Contents		Rev 11/21/2025
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Benthimermis Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Marimermithidae Menu		Feeding		References
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Classification:

         Enoplea

Dorylaimia

Mermithida

    Mermithina

               Mermithoidea

                           Marimermithidae

            Benthimermis Petter, 1980

Type species of the genus: Benthimermis aptera Petter, 1982

Benthimermis now considered a junior synonym of Trophomera (Miltjutin, 2006)

Rubzov and Platonova (1974) erected the new family Marimermithidae to include Benthimermis and two other genera, Trophomera Rubzov & Platonova, 1974 and Thalassonema Ward, 1933, which were the only genera known at the time.

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Morphology and Anatomy:

• Slender nematodes up to 15 cm long with a diameter around 500 um
• Anterior end is rounded, posterior truncate and conical terminating in an axial spine
•  Cuticle thin and transparent so that trophosome and genital system are visible.
• Cuticle with very fine annnulation. numerous conical somatic setae 5 - 6 um long distributed laterally throughout the body
• Cuticle in cephalic region with very fine punctations extending from anterior end apex to almost the level of amphids
• Mouth opening is absent, but there is a central apical light spot surrounded by six minute marks that may be vestigial subsurface cephalic sensilla; also, four cephalic setae 7 - 8.5 um long
• Amphids with small transversely oval pore-like opening 8 - 9 um wide located 170 - 260 um from cephalic apex
• Esophagus vestigial without a lumen
• Midgut is a trophosome made up of large radial cells and a very thin axial internal lumen. The trophosome cells are filled with various inclusions,
• Nerve ring  embedded in the anterior trophosome.
• No anus is present at the posterior end of the body.
• Terminal spine is prominent, 750 - 1200 um long, solid,cuticular without cells or cell processes

Female:

• Amphidelphic, germinal zone of  the ovaries B. litoralis extends the length of the gonad (hologonic ovary), whereas the ovaries of smaller Benthimermis species are telogonic.
• Vulva at about mid-body.
• Males not seen, neither spermatheca or sperm were seen in female genital system

Ref: Miljutin and Tchesunov, 2001.

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Distribution:

Benthimermis megala was described from bottom sediments of the deep-sea off the coast of Norway  at depths of 2668-2904 m (Miljutin and Tchesunov, 2001).

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Feeding:

Food Sources and Feeding strategies for the genus Benthimermis

Juveniles parasitic in marine invertebrates, adults apparenly not feeding. The intra-cellular inclusions and shrinkage of the trophosome, together with degradation of the reproductive organs, suggest that the trophosome functions to store nutrients that are expended during the free-living adult stage in sediments (Miljutin and Tchesunov, 2001).

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Biology and Ecology:

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Life Cycle:

Like the mermithids of fresh-water and soil environments (Order Mermithida), the larval stages of benthimermithids parasitise the body cavities and internal organs of invertebrate hosts, including polychaetes, priapulids, various crustaceans, holothuroids and free-living nematodes. Adult or late larval stages leave the host and enter a nonparasitic phase in which they reproduce but, based on their modified digestive system and lack of a mouth, apparently do not feed. So, larval stages parasitize benthic invertebrates, while non-feeding adult stages reproduce in benthic sediment  (Miljutin and Tchesunov, 2001).

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Ecosystem Functions and Services:

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Management:

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References:

Miljutin, D.M. and Tchesunov, A.V. 2001. On the histological anatomy of Benthimermismegala Petter, 1987, a giant nematode from the Norwegian deep-sea (Nematoda: Benthimermithidae). Nematology 3:491-502.

Miljutin, D.M. 2006. The genus Trophomera Rubtsov & Platonova, 1974 with description of T. litoralis sp. n. (Nematoda: Benthimermithidae) from the tidal zone of the Kuril Archipelago and proposal of Benthimermis Petter, 1980 as a junior synonym. Nematology 8:411-423,  https://doi.org/10.1163/156854106778493457

Rubtsov, I. A., & Platonova, T. A. (1974). A new family of marine parasitic nematodes. Zoologicheskii Zhurnal, 53, 1445-1458.

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Copyright © 1999 by Howard Ferris.
Revised: November 21, 2025