Barreleyes - sama jelah nak PDF

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Description

Barreleyes, also known as spook fish, are small deep-sea argentiniform fish comprising the family Opisthoproctidae found in tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans. Wikipedia Scientific name: Opisthoproctidae Higher classification: Argentiniformes Rank: Family Did you know: The ultrasensitive tubular eyes of the barreleye fish detect their prey even in the pitch dark environment. prezi.com

Macropinna microstoma (Barreleye)

Opisthoproctus soleatus

Scientific classification Kingdom:

Animalia

Phylum:

Chordata

Class:

Actinopterygii

Order:

Argentiniformes

Family:

Opisthoproctidae

All species have large, telescoping eyes, which dominate and protrude from the head, but are enclosed within a large transparent dome of soft tissue. [5] These eyes generally gaze upwards, but can also be directed forwards.[6] The opisthoproctid eye has a large lens and a retina with an exceptionally high complement of rod cells and a high density of rhodopsin (the "visual purple" pigment); no cone cells are present. To better serve their vision, barreleyes have large, dome-shaped, transparent heads; this presumably allows the eyes to collect even more incident light and likely protects the sensitive eyes from the nematocysts (stinging cells) of the siphonophores, from which the barreleye is believed to steal food. It may also serve as an accessory lens (modulated by intrinsic or peripheral muscles), or refract light with an index very close to seawater. Dolichopteryx longipes is the only vertebrate known to use a mirror (as well as a lens) in its eyes for focusing images.

The toothless mouth is small and terminal, ending in a pointed snout. As in related families (e.g. Argentinidae), an epibranchial or crumenal organ is present behind the fourth gill arch. This organ—analogous to the gizzard—consists of a small diverticulumwherein the gill rakers insert and interdigitate for the purpose of grinding up ingested material. The living body of most species is a dark brown, covered in large, silvery imbricate scales, but these are absent in Dolichopteryx, leaving the body itself a transparent white. In all species, a variable number of dark melanophores colour the muzzle, ventral surface, and midline. In all species, the fins are spineless and fairly small; in Dolichopteryx however, the pectoral fins are greatly elongated and wing-like, extending about half the body's length, and are apparently used for stationkeeping in the water column. The pectoral fins are inserted low on the body, and in some species, the pelvic fins are inserted ventrolaterally rather than strictly ventrally. Several species also possess either a ventral or dorsal adipose fin, and the caudal fin is forked to emarginated. The anal fin is either present or greatly reduced, and may not be externally visible; it is strongly retrorse in Opisthoproctus. A single dorsal fin originates slightly before or directly over the anal fin. A perceptible hump in the back begins just behind the head. The gas bladder is absent in most species, and the lateral line is uninterrupted. The branchiostegal rays (bony rays supporting the gill membranes behind the lower jaw) number two to four. The javelin spookfish (Bathylychnops exilis) is by far the largest species at 50 centimetres (20 in) standard length; most other species are under 20 centimetres (7.9 in).

Barreleyes inhabit moderate depths, from the mesopelagic to bathypelagic zone, circa 400–2,500 m deep. They are presumably solitary and do not undergo diel vertical migrations; instead, barreleyes remain just below the limit of light penetration and use their sensitive, upward-pointing tubular eyes—adapted for enhanced binocular vision at the expense of lateral vision—to survey the waters above. The high number of rods in their eyes' retinae allows barreleyes to resolve the silhouettes of objects overhead in the faintest of ambient light (and to accurately distinguish bioluminescent light from ambient light), and their binocular vision allows the fish to accurately track and home in on small zooplankton such as hydroids, copepods, and other pelagic crustaceans....