Placentonema gigantissima		Contents		Rev 01/21/2025
Sperm Whale Placenta Nematode		Classification		Hosts
		Morphology and Anatomy		Life Cycle
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Classification:

Chromadorea

  Chromadoria

   Rhabditida

Spirurina

              Habronematoidea

               Tetrameridae

  Crassicaudinae

Placentonema gigantissima Gubanov, 1951

Type species of the genus

Parasite of the placenta and other tissues of sperm whales

Synonyms:

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Morphology and Anatomy:

Placentonema gigantissima differs the genus Crassicauda in having caudal alae with stub-like papillae in the male and,  in the female, with multiple branching of the reproductive tract into 32 uteri

• Very large nematodes; females >8 meter length; body cylindrical, tapering at extremities
• cuticle thin, transparent cuticle without transverse striation except at head end.
• Oral orifice oval-shaped with two simple lateral lips, each with 2 papilla and one amphid at its base.
• Pharynx cylindroid, esophagus separated distinctly into muscular and glandular parts.

Placentonema gigantissima - original description from Gubanov, 1951 Source Wikipedia, accessed January 19, 2025	Placentonema gigantissima - Gubanov, 1951 paper translated to English Source Wikipedia, accessed January 19, 2025

Poaterior end of male (left) and female (right).  Male with leptoderan bursa and arrangement of caudal papillae, Female with position of anus (A) and vulva (B), and branching of genital tract into 32 uteri. Drawings from Gubanov, 1951

Female:

• Length 6.75 - 8.4 m, width 1.5-2.5 cm

•  Pharynx 0.12 mm long, 0.008 mm wide. Muscular part of esophagus 2.7-2.8 mm long, 0.2-0.26 mm wide; glandular part 63.6 mm long and 0.56-0.6 mm wide.

• Tail end rounded, with pear-shaped elongation, tail narrowing sharply at 11.3 mm from the tail end.

• Anus 0.8-1 m from the tail end, anal body width 2.9 mm.

• Vulva in posterior of body, 12.4-14.8 mm anterior to anus;. vagina short

• Multidelphic-prodelphic. Uterus multiple branching into 32 uteri.

• Mature eggs oval, 0.049 mm long and 0.030 mm wide, with completely formed juvenile inside.

Male:

• Length 2.04-3.75 m, width 8-9 mm.

• Oral orifice up to 0.048 mm long and 0.016 wide.

• Pharynx 0.14 mm long and 0.008 mm wide. Anterior muscular part of oesophagus up to 2.18-4.0 mm long and 0.1-0.14 mm wide. Glandular part of oesophagus 67.7 mm long, 0.6 mm wide.

• Tail end blunt, curved ventrally.

• Cloacal orifice 1.4-1.6 mm from posterior body end.

• Caudal alae form a leptoderan bursa 1.26-1.4 mm long and up to 0.6-0.7 mm wide,

• At base of caudal alae are four precloacal pairs and three postcloacal pairs of stub-like granular papillae. Three pairs of
  low papillae of the same structure are situated posteriorly to alae ; also, two adanal papillae.

• Tail end up to 1.4-1.9 mm wide at cloaca.

Ref: Gubanov, 1951

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Distribution:

Sperm whale hosts in the lower latitudes of the southern hemisphere. Species described from whales near the Kuril Islands, Russian far east.

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Feeding:

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Biology and Ecology:

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Life Cycle:

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Ecosystem Functions and Services:

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Management:

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References:

Delyamure, S.L. 1955. DHelminthofauna of marine mammals (Ecology and Phylogeny). Gel'mintologicheskaya Laboratoria, Akademiya Nauk SSSR, Moskva. English translation: Israel Program for Scientific Translations, Jerusalem, 1968 pp 520.

Gubanov, N.M.  A giant nematode from the placenta of cetaceans; Placenttnema gigantissima n.g. n.sp. Doklady Akademii Nauk SSSR. 77(6): 1123-1125.

Hermosilla, C., Hirzmann, J.; Silva, L. M.R.; Brotons, J M.; Cerda, M.; Prenger-Berninghoff, E.; Ewers, C.; Taubert, A. 2018.  Occurrence of anthropozoonotic parasitic infections and faecal microbes in free-ranging sperm whales (Physeter macrocephalus) from the Mediterranean Sea. Parasitology Research 117: 2531-2541. doi:10.1007/s00436-018-5942-3

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Copyright 1999 by Howard Ferris.
Revised: January 21, 2025.