The triplewart seadevil (''Cryptopsaras couesii'') is a sea devil of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Ceratiidae Sea devils are the family of deep-sea anglerfish known as the Ceratiidae, from the Greek ''keras'', "horn", referring to the bioluminescent lure that projects from the fishes' forehead. They are among the most widespread of the anglerfishes, f ...

and the order Lophoiiformes. This species is the only member of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

. Noted for its extreme sexual dimorphism, the triplewart seadevil's length ranges from 20 to 30 cm for females and 1 to 3 cm for males.

Distribution

Triplewart seadevils are ceratioids commonly found worldwide in all major oceans. They are seen in depths ranging from 75 to 4000 m (250 to 13,100 ft), with the majority of specimens found in the mesopelagic and bathypelagic zones between 500 and 1250 m (1600 to 4100 ft). It is dispersed from the deep ocean to shallower water because its weak swimming power allows it to be carried over long distances by ocean currents.

Morphology

Female triplewart seadevils have a laterally compressed, elongated body with a large head and a mouth that is nearly vertical when closed. It has 2 to 3 rows of irregular depressible teeth, with significantly larger teeth on the lower jaw than the smaller upper jaw. The body is covered by deeply embedded hollow spines. Only the tips show and there are no conical bone plates. The 3 lateral caruncles have club-shaped glands that secrete a slime containing luminous granules. Adult females have jet-black pigmentation while juveniles are dark brown. The triplewart seadevil uses an

illicium ''Illicium'' is a genus of flowering plants treated as part of the family Schisandraceae,

, a modified dorsal spine on the snout, to lure prey. This apparatus is primarily composed of a terminating

esca The anglerfish are fish of the teleost order Lophiiformes (). They are bony fish named for their characteristic mode of predation, in which a modified luminescent fin ray (the esca or illicium) acts as a lure for other fish. The luminescence co ...

or lure supported by an extremely long

pterygiophore A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

bone encased in a dermal sheath. Winding muscles control the anterior and posterior movement of the bone, suggesting extension and retraction by rotation. The terminal esca contains

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

bacterial

symbionts Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

, creating a glowing lure for their prey. BMC - Ceratiidae-Cryptopsaras

Sexual dimorphism

The species displays extreme

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, where dwarfed males parasitize the larger females. Their specialized jaw has an anterior pair of denticular teeth that are longer than their posterior pair. Males permanently attach themselves to the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

side of females with this specialized jaw meant for grasping a female mate. Once attached, tissue fusion occurs, permanently binding the mouth and one side of the male to the surface of the female. After attachment, the male becomes dependent on the female for blood-circulated nutrients due to the fusion of the circulatory and digestive systems. This case of extreme sexual dimorphism is favored by

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...

due to the random dispersal of individuals. If one of the relatively numerous males is fortunate enough to encounter a female, it attaches for the remainder of its life. This significantly increases the chance of reproduction for the individual and therefore increases its fitness.

Reproduction

Cryptopsaras couesii triplewart seadevil

Female triplewart seadevils are receptive to parasitic males at a young age. Once past

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

sexual parasitism Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The geni ...

may occur at almost any size (as small as 15 mm.) Despite this, the percentage of reproducing individuals is small. Of 600 metamorphosed females studied, only 6.2% were parasitized. Spawning events occur more than once a year, and the Atlantic Ocean contains triplewart seadevil larvae for most of the year, with summer having the greatest occurrences. The seadevil's method of sexual parasitism leads to the female to be akin to a self-fertilizing

hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...

. This is due to the nature of tissue fusion between mates and the continuous production of sperm by the male. Unlike all other ceratioids, males do not have large nostrils for tracking species-specific

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s emitted by the female. Instead, they have large eyes that degenerate upon attachment to the female.

References

External links

* * {{Taxonbar, from=Q1851870 Ceratiidae Fish described in 1883 Taxa named by Theodore Gill