User:Sophiaschortmann/Snailfish

Note for reviewers: bolded text below are our teams contributions that will be posted to the wiki page

Phylogeny

Species of deep-sea snailfish have been studied and compared to other ray-finned fishes (also known as teleosts) to analyze how they have evolved to adapt to harsh conditions. The genomes of both the Yap hadal Snailsih and Mariana hadal Snailfish have been found to contain an abundance of the fmo3 gene, which produces the trimethylamine N-oxide (TMAO) protein stabilizer. I added the rest of this info directly to the wiki page

Description

The snailfish family is poorly studied and few specifics are known. Their elongated, tadpole-like bodies are similar in profile to the rattails. Their heads are large (compared to their size) with small eyes; their bodies are slender to deep, tapering to very small tails. The extensive dorsal and anal fins may merge or nearly merge with the tail fin. Snailfish are scaleless with a thin, loose gelatinous skin; some species, such as Acantholiparis opercularis have prickly spines, as well. Their teeth are small and simple with blunt cusps. The deep-sea species have prominent, well-developed sensory pores on the head, part of the animals' lateral line system.

The pectoral fins are large and provide the snailfish with its primary means of locomotion although they are fragile. In some species such as the antarctic Paraliparis devriesi, the pectoral fins have an expanded somatosensory system, including a taste bud. The snailfish are benthic fish with pelvic fins modified to form an adhesive disc; this nearly circular disc is absent in Paraliparis and Nectoliparis species. Research has revealed that maximum depth of living can be a significant predictor for loss of the pelvic disk is certain species of snailfish. Based on phylogenetic analysis, this ancestral feature has been lost three separate times in Snailfish. Snailfish range in size from Paraliparis australis at 5 cm (2.0 in) to Polypera simushirae at some 77 cm (30 in) in length. The latter species may reach a weight of 11 kg (24 lb), but most species are smaller. Snailfish are of no interest to commercial fisheries.

It was difficult to initially study snailfish species that dwell at deeper levels because they would explode upon being brought to the surface, but researchers did manage to study the bones of the animal. A new species of snailfish, Pseudoliparis swirei, has recently been collected (2014) in the Mariana Trench at depths 6898–7966 m. This unique snailfish species has transparent, unpigmented skin and scales, thin and incompletely ossified bones, an inflated stomach and a non-closed skull. Pseudoliparis swirei has various adaptations to be able to survive the extreme environment of deep-sea trenches. Genomic analyses revealed molecular adaptations consistent with pressure-tolerant cartilage, loss of visual function and skin color, enhanced cell membrane fluidity and transport protein activity, and increased protein stability. The eyes of Pseudoliparis swirei have been analyzed using liquid chromatography-mass spectrometry/mass spectrometry. A total of 2088 proteins were identified in the eye proteome, and abundant metabolic activity was identified which proved that the eye is still a functional visual organ. One rhodopsin was identified in the eye proteome and it was concluded that it may be sensitive to dim blue light. Heat shock proteins and chaperonin-containing T-complex protein 1 were also highly expressed in the eye. Despite previous evidence, it has been concluded that the Hadal snailfish may have a residual ability to see.

Reproduction and life span

Reproductive strategies vary extensively among snailfish species, though it is thought that many abyssal benthic snailfish spawn seasonally and for relatively long intervals. Based on the literature, it appears that all species lay eggs that are relatively large in size (diameter up to 9.4 mm or 0.37 in) but the number of eggs is species dependent. The larger size of eggs in hadal snailfish species indicates continuous spawning. However, some deposit their egg mass among cold-water corals, kelp, stones, or xenophyophores and males will sometimes guard the egg mass. At least one species, Careproctus ovigerus of the North Pacific, is known to practice mouth brooding where the male snailfish carries the developing eggs around in his mouth. Some other species of the genus Careproctus, are parasitic, laying their eggs in the gill cavities of king crabs. The eggs put pressure on the crabs gills which can cause the gill tissue to be damaged or die altogether. However, the survival of snailfish larvae has shown to increase by snailfish utilizing the crab host species as a way to care for and aerate their eggs. The eggs themselves are self-adhesive and tend to form masses that replicate the shape of the internal branchial chambers of crabs. Additionally, at least one species of snailfish, Caraproctus pallidus, that utilize the golden king crab as a host, has larvae with a lower energy content that normal for most marine fish. A possible explanation for starting life with less energy, is due to the energy and saftey provided by the king crabs and the adult snailfish not needed to expend as much energy producing a really energy-rich yolk sac. A different species, Careproctus rhodomelas, was found to be a batch spawner, laying multiple batches of large eggs multiple times throughout its lifetime. After the eggs hatch, some species rapidly reach the adult size and only live for about one year, but others have life spans of more than a decade.

Very little is known about snailfish courtship behavior but males of Careproctus pallidus are believed to wiggle their bodies as attractive or aggressive display. It is thought that in an environment so dark, it is hard to find and win contests for a mate. Therefore, snailfish use hydrodynamic signals that are felt by the mechanosensory lateral line to communicate.

Diet

In a 2007 study of fish in the hadal zone, it was revealed that snailfish usually feed on amphipods, which were also attracted to the chum that the researchers left out. Larval snailfish feed on a mix of plankton, small and large copepods, and amphipods. The diet of larval snailfish contains 28 food categories, mainly copepods and amphipods.

Snailfish prey can be grouped into six main categories: gammarid, krill, natantian decapods, other crustaceans, fish, and others. Size also affects snailfish diets. Species smaller than 50 mm primarily eat gammarids, while species larger than 100 mm primarily eat natantian decapods. Species larger than 150 mm have the highest proportion of fish in their diet. Larger snailfish species tend to be piscivorous.

In the Okhotsk Snailfish (Liparis ochotensis), as the organism grows, the ratio between food intake and body weight actually changes, and it is also highly dependent on the season. When the environment sees an increase in shrimp and crangonidae levels, there is also a decrease in decapods. There are also snailfish localized to the Terpeniya Bay that purely eat zooplankton, setting them apart from other snailfish.

The snailfish that live in the northern hemisphere also display a higher starvation tolerance, and while it is still being studied, it is suggested that this is due to the triglycerol and cholesterol levels in this species. The snailfish have different lipid concentrations depending on their habitat, making some of them more suited for longer periods without feeding than others.

The predator method that the species Simushir Snailfish (Polypera simushirae) is really interesting because it uses an ambush method to surprise its prey. It has the ability to blend into the ground, waiting to surprise the next prey to wander in its path. The primary prey for this species is fish, making up 97.7% of the overall food weight.