Eptatretus bischoffii
Encyclopedia
Eptatretus bischoffii is a common hagfish
of the genus Eptatretus
. Its maximum length is 55 centimetres (21.7 in). It lives in a demersal, non-migratory, marine habitat with its depth range between 8–50 m. It can survive in only temperate zones. These organisms are found in the South Pacific
, mainly, Chile
. It is harmless to humans.
The mode of reproduction in this kind of organism is external. The copulatory organs are absent. The gonad
s of hagfishes are situated in the peritoneal cavity
. The ovary
is found in the anterior portion of the gonad, and the testis is found in the posterior part. The animal becomes female if the cranial part of the gonad develops or male if the caudal part undergoes differentiation. If none develops, then the animal becomes sterile. If both anterior and posterior parts develop, then the animal becomes a functional hermaphrodite. However, hermaphroditism being characterised as functional needs to be validated by more reproduction studies.
The eggs develop in the demersal areas. The shape of the eggs are elongated. The egg contains a single micropylar opening
located at the animal pole. It is situated at the bottom of a micropylar cup which lies between the anchor filaments. The single filaments are 3.2–4.9 mm (0.125984251968504–0.192913385826772 in) long and have an anchor-shaped apical end. The number of filaments varies around 50 but is always smaller on the vegetative end. On both ends of laid eggs, the filaments are enveloped by a gel-like matrix intertwined with large cytoskeletal
biopolymer
s (keratin
-like intermediate filaments) of possible holocrine origin.
Hagfish
Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...
of the genus Eptatretus
Eptatretus
Eptatretus is a large genus of hagfish. It has at around 48 described species at present.-Species:* Eptatretus alastairi Mincarone & Fernholm, 2010* Eptatretus ancon...
. Its maximum length is 55 centimetres (21.7 in). It lives in a demersal, non-migratory, marine habitat with its depth range between 8–50 m. It can survive in only temperate zones. These organisms are found in the South Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, mainly, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. It is harmless to humans.
The mode of reproduction in this kind of organism is external. The copulatory organs are absent. The gonad
Gonad
The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...
s of hagfishes are situated in the peritoneal cavity
Peritoneal cavity
The peritoneal cavity is a potential space between the parietal peritoneum and visceral peritoneum, that is, the two membranes that separate the organs in the abdominal cavity from the abdominal wall...
. The ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
is found in the anterior portion of the gonad, and the testis is found in the posterior part. The animal becomes female if the cranial part of the gonad develops or male if the caudal part undergoes differentiation. If none develops, then the animal becomes sterile. If both anterior and posterior parts develop, then the animal becomes a functional hermaphrodite. However, hermaphroditism being characterised as functional needs to be validated by more reproduction studies.
The eggs develop in the demersal areas. The shape of the eggs are elongated. The egg contains a single micropylar opening
Micropyle
A micropyle is small opening in the surface of an ovule, through which the pollen tube penetrates, often visible as a small pore in the ripe seed....
located at the animal pole. It is situated at the bottom of a micropylar cup which lies between the anchor filaments. The single filaments are 3.2–4.9 mm (0.125984251968504–0.192913385826772 in) long and have an anchor-shaped apical end. The number of filaments varies around 50 but is always smaller on the vegetative end. On both ends of laid eggs, the filaments are enveloped by a gel-like matrix intertwined with large cytoskeletal
Cytoskeleton
The cytoskeleton is a cellular "scaffolding" or "skeleton" contained within a cell's cytoplasm and is made out of protein. The cytoskeleton is present in all cells; it was once thought to be unique to eukaryotes, but recent research has identified the prokaryotic cytoskeleton...
biopolymer
Biopolymer
Biopolymers are polymers produced by living organisms. Since they are polymers, Biopolymers contain monomeric units that are covalently bonded to form larger structures. There are three main classes of biopolymers based on the differing monomeric units used and the structure of the biopolymer formed...
s (keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
-like intermediate filaments) of possible holocrine origin.