DEEP SEA FISH

DEEP SEA
FISH

creatures that lurk in the depths

EVOLUTION

The earliest known records of deep-sea fish are trace fossils of feeding and swimming behavior attributed to unidentified neoteleosts (referable to the ichnogenera Piscichnus and Undichna), from the Early Cretaceous (130-million-year-old) Palombini Shale of Italy, which is thought to have been deposited in the abyssal plain of the former Piemont-Liguria Ocean. Prior to the discovery of these fossils, there was no evidence for deep-sea fish older than 50 million years in the Paleogene. The Cretaceous origin for most modern deep-sea fish has been further affirmed with phylogenetic studies such as those of aulopiform fish, which indicate that many deep-sea lineages of these groups originated around this time. It has been speculated that deep-sea ecosystems may have been inhospitable to vertebrate life prior to an increased influx of nutrients into the ocean during the Late Jurassic and Early Cretaceous following the rise of angiosperms on land, which led to an increase in abyssal invertebrate life, allowing fish to in turn colonize these ecosystems. However, some modern deep-sea fish such as holocephalians are descendants of much older lineages, indicating that much earlier colonizations of the deep-sea by vertebrates may have occurred, although no fossil evidence of this is known.

ENVIRONMENT

In the deep ocean, the waters extend far below the epipelagic zone, and support very different types of pelagic fishes adapted to living in these deeper zones. In deep water, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. Its origin lies in activities within the productive photic zone. Marine snow includes dead or dying plankton, protists (diatoms), fecal matter, sand, soot and other inorganic dust. The "snowflakes" grow over time and may reach several centimetres in diameter, travelling for weeks before reaching the ocean floor. However, most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1000 m of their journey, that is, within the epipelagic zone. In this way marine snow may be considered the foundation of deep-sea mesopelagic and benthic ecosystems: As sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. Since there is no light in the deep sea (aphotic), there is a lack of primary producers. Therefore, most organisms in the bathypelagic rely on the marine snow from regions higher in the vertical column.

COMMON
CHARACTERISTICS

SIGHT

Many of these organisms
are blind and rely on their other
senses, such as sensitivities to
changes in local pressure and smell,
to catch their food and avoid being
caught. Those that aren't blind
can use bioluminescent light.

BIO
LUMINESCENSE

Bioluminescent organisms
are capable of producing light
biologically through the agitation
of molecules of luciferin, which
then produce light. This process
must be done in the presence
of oxygen.

FOOD

Also, animals in the pelagic
environment are sparse and food
doesn't come along frequently.
Because of this, organisms need
adaptations that allow them to
survive. Some have long feelers
to help them locate prey or
attract mates in the black
of the deep ocean.


PRESSURE

Their bodies are elongated
with weak, watery muscles and
skeletal structures. Since so much
of the fish is water, they are not
compressed by the great pressures
at these depths. They are slimy,
without scales.

MESOPELAGIC FISH

Below the epipelagic zone, conditions change rapidly. Between 200 m and about 1000 m, light continues to fade until there is almost none. Temperatures fall through a thermocline to temperatures between 3.9 °C (39 °F) and 7.8 °C (46 °F). This is the twilight or mesopelagic zone. Pressure continues to increase, at the rate of one atm every 10 m, while nutrient concentrations fall, along with dissolved oxygen and the rate at which the water circulates.

HELMET JELLYFISH

Helmet jellyfish reach a body size of up to 30 cm (12 in). The average wet weight of the jellyfish is 540 grams. Overall, helmet jellyfish have a uniform size.They consist 90% of water, the rest being tissue and gelatinous mass, which give the animals their form. They light themselves from within by means of bioluminescence, the red flashes serving as a signal amongst themselves. Between their marginal lobes sit small sense bulbs, by which the helmet jelly can distinguish between light and dark; they have been observed to avoid light. Their nature of avoiding light has given them the title of being photophobic. They have a biochemical content that consists of having a small amount of carbohydrates, average amount of lipids, and a large content of protein. The helmet jellyfish have twelve tentacles that consist of layers of endoderm and mesoglea, but each jellyfish can have a different type of tentacle posture.

TASSELED ANGLERFISH

Helmet jellyfish reach a body size of up to 30 cm (12 in). The average wet weight of the jellyfish is 540 grams.[2] Overall, helmet jellyfish have a uniform size.[3] They consist 90% of water, the rest being tissue and gelatinous mass, which give the animals their form. They light themselves from within by means of bioluminescence, the red flashes serving as a signal amongst themselves. Between their marginal lobes sit small sense bulbs, by which the helmet jelly can distinguish between light and dark; they have been observed to avoid light. Their nature of avoiding light has given them the title of being photophobic. They have a biochemical content that consists of having a small amount of carbohydrates, average amount of lipids, and a large content of protein. The helmet jellyfish have twelve tentacles that consist of layers of endoderm and mesoglea, but each jellyfish can have a different type of tentacle posture.

LANTERNFISH

Lanternfish typically have a slender, compressed body covered in small, silvery deciduous cycloid scales (ctenoid in four species), a large bluntly rounded head, large elliptical to round lateral eyes (dorsolateral in Protomyctophum species), and a large terminal mouth with jaws closely set with rows of small teeth.Lanternfish are well known for their diel vertical migrations: during daylight hours, most species remain within the gloomy bathypelagic zone, between 300 and 1,500 m (980 and 4,920 ft) deep, but towards sundown, the fish begin to rise into the epipelagic zone, between 10 and 100 m (33 and 328 ft) deep. The lanternfish are thought to do this to avoid predation, and because they are following the diel vertical migrations of zooplankton, upon which they feed.Most species remain near the coast, schooling over the continental slope.

DEEP SEA MYCID

Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in this pouch and are not free-swimming characterises the order. The head of a mysid bears two pairs of antennae and a pair of large, stalked eyes. The head and first segment (or sometimes the first three segments) of the thorax are fused to form the cephalothorax. The eight thoracic segments are covered by the carapace which is attached only to the first three. Some species are benthic (living on the seabed) and others pelagic (living in mid-water), but most are found close to, crawling on or burrowing into the mud or sand. Most marine species are benthic by day but leave the seabed at night to become planktonic.

BATHYPELAGIC FISH

Below the epipelagic zone, conditions change rapidly. Between 200 m and about 1000 m, light continues to fade until there is almost none. Temperatures fall through a thermocline to temperatures between 3.9 °C (39 °F) and 7.8 °C (46 °F). This is the twilight or mesopelagic zone. Pressure continues to increase, at the rate of one atm every 10 m, while nutrient concentrations fall, along with dissolved oxygen and the rate at which the water circulates.

VIPERFISH

A viperfish is any species of marine fish in the genus Chauliodus. Viperfishes are mostly found in the mesopelagic zone and are characterized by long, needle-like teeth and hinged lower jaws. A typical viperfish grows to lengths of 30 cm (12 in). Viperfishes undergo diel vertical migration and are found all around the world in tropical and temperate oceans. Viperfishes are capable of bioluminescence and possess photophores along the ventral side of their body, likely used to camouflage them by blending in with the less than 1% of light that reaches to below 200 meters depth.Although it may appear to be covered in scales, viperfishes do not possess scales. Rather, they are covered by a thick, transparent coating of unknown substance. Extremely large, fang-like teeth give the fish a slightly protruded lower jaw.

ANGLERFISH

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 comes from symbiotic bacteria, which are thought to be acquired from seawater, that dwell in and around the sea. Some anglerfish are notable for extreme sexual dimorphism and sexual symbiosis of the small male with the much larger female, seen in the suborder Ceratioidei, the deep sea anglerfish. In these species, males may be several orders of magnitude smaller than females.Anglerfish occur worldwide. Some are pelagic (dwelling away from the sea floor), while others are benthic (dwelling close to the sea floor).

VAMPIRE SQUID

The vampire squid can reach a maximum total length around 30 cm (1 ft). Its 15-centimetre (5.9 in) gelatinous body varies in colour from velvety jet-black to pale reddish, depending on location and lighting conditions. A webbing of skin connects its eight arms, each lined with rows of fleshy spines or cirri; the inner side of this "cloak" is black. Only the distal halves (farthest from the body) of the arms have suckers. The vampire squid is an extreme example of a deep sea cephalopod, thought to reside at aphotic (lightless) depths from 600 to 900 metres (2,000 to 3,000 ft) or more. Within this region of the world's oceans is a discrete habitat known as the oxygen minimum zone (OMZ). Within the zone, the saturation of oxygen is too low to support aerobic metabolism in most complex organisms. The vampire squid is the only cephalopod able to live its entire life cycle in the minimum zone, at oxygen saturations as low as 3%.

PELICAN EEL

The pelican eel's most notable feature is its large mouth, which is much larger than its body. The mouth is loosely hinged, and can be opened wide enough to swallow a fish much larger than the eel itself. The lower jaw is hinged at the base of the head, with no body mass behind it, making the head look disproportionately large. Its jaw is so large that it is estimated to be about a quarter of the total length of the eel itself.While typically in a folded state, the pelican eel's mouth has the capacity to change to an inflated shape when hunting, giving the mouth its notably massive appearance. This transformation is possible due to the dual-mode biological morphing mechanism that takes place: geometric unfolding of the mouth followed by stretching. When the pelican eel is in pursuit of prey and opens its mouth, the head and jaw structure unfold and spread horizontally.

SOURCES
  1. https://en.wikipedia.org/wiki/Viperfish
  2. https://en.wikipedia.org/wiki/Mysida
  3. https://en.wikipedia.org/wiki/Rhycherus_filamentosus
  4. https://en.wikipedia.org/wiki/Anglerfish
  5. https://en.wikipedia.org/wiki/Vampire_squid
  6. https://en.wikipedia.org/wiki/Pelican_eel
  7. https://en.wikipedia.org/wiki/Lanternfish
  8. https://en.wikipedia.org/wiki/Helmet_jellyfish