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| Okamejei panayensis | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Superorder: | Batoidea |
| Order: | Rajiformes |
| Family: | Rajidae |
| Genus: | Okamejei |
| Species: | O. panayensis |
| Binomial name | |
| Okamejei panayensis | |
Okamejei panayensis is a demersal fish belonging to the skate family, occurring in nearshore temperate environments and deep-water tropical and boreal regions. [1]
Okamejei panayensis has been found in the waters off the South China Sea near Iloila, Philippines, close to the Philippine Rise. [2] This area is on a continental ridge, with muddy sediment, inland bays and wide tidal flats where other Rajidae species are known to reside and spawn. [3]
Like all skates, O. panayensis has a depressiform, cartilaginous, rhombic body that allows it to move closely along the seafloor. [4] It has a mouth on the ventral side and a set of spiracles behind its eyes. It has ventral sensory pores (similar to ampullae in other forms of Chondrichthyes), with a lack of pores on the central abdominal region and pelvic lobes. [2]
The ventral surface of the disk is broadly white, with a pale brown margin, and it is darkly pigmented at the bases of the pectoral fins and the nasal curtain. One distinguishable characteristic of the species is its densely scattered black spots on the dorsal disc, that do not come together to form patches. This feature alongside a yellowish-brown dorsal surface helps to visually differentiate it from O. hollandi and O. mengae, which are otherwise similar in appearance. [4]
Okamejei panayensis has the least amount of pectoral fin radials of any organism in its genus, tallying in at 75 to 76 radials, and the second smallest preorbital snout length, which measures 14.3% of the total body length. [2]
Pelagic food sources such as squid, krill, shrimp, crustaceans, shelled mollusks, and other benthic invertebrates are typically eaten by demersal elasmobranchs like O. panayensis, indicating that this species likely has an equivalent diet. [5]
The size of the O. panayensis population is unknown. However, most Rajidae species are susceptible to overfishing due to their low reproductive rate and a direct relationship between stock size and recruitment. [6]
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera. Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae, but are now considered as distinct families. Alternatively, the name "skate" is used to refer to the entire order of Rajiformes.
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks, rays, skates, and sawfish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.
An egg case or egg capsule, often colloquially called a mermaid's purse, is the casing that surrounds the eggs of oviparous chondrichthyans. Living chondricthyans that produce egg cases include some sharks, skates and chimaeras. Egg cases typically contain one embryo, except for big skate and mottled skate egg cases, which contain up to 7 embryos. Oviparity is completely absent in the superorder Squalomorphii. Egg cases are also thought to have been produced by some extinct chondricthyan groups, such as hybodonts and xenacanths.
Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule.
In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some species of shark such as the sawshark. Barbels house the taste buds of such fish and are used to search for food in murky water.
Anguilla bengalensis bengalensis, the Indian mottled eel, is a subspecies of eel in the genus Anguilla. It is found throughout the Indian subcontinent and neighbouring regions including the East Indies. The Indian mottled eel is valued as a food fish. The mucus of this eel is used in a medicine for arthritis. It is known by numerous common names in the native languages of the regions it inhabits.
Bathyraja is a large genus of skates in the family Arhynchobatidae.
Raja, also known as raia, is a genus of skates in the family Rajidae containing 16 species. Formerly a wastebasket genus, many species historically categorized here have been moved to other genera in the family, such as Amblyraja, Beringraja, Dipturus, Leucoraja and Rostroraja. Raja are flat-bodied, cartilaginous fish with a rhombic shapes due to their large pectoral fins extending from or near from the snouts to the bases of their tails. Their sharp snouts are produced by a cranial projection of rostral cartilage. The mouth and gills are located on the underside of the body. They may be either solid-coloured or patterned, and most skates have spiny or thorn-like structures on the upper surface, while some species contain weak electrical organs within their tails. Mating typically occurs in the spring and the female lays numerous eggs per clutch which are encapsulated in leathery cases, commonly known as "mermaid’s purses". Species vary in size, ranging from about 40 to 140 cm (1.3–4.6 ft) in length. These bottom-dwellers are active during both day and night, and typically feed on molluscs, crustaceans and fish. Raja skates are found in the East Atlantic, also in the Mediterranean, and western Indian Ocean, ranging from relatively shallow water to a depth of 800 m (2,600 ft). Skates and related species have fossil records dating from the Upper Cretaceous period, thus this well-adapted species is quite ancient.
The spotback skate is a species of fish in the family Arhynchobatidae. It is found off the Atlantic coasts of Argentina, Brazil, and Uruguay where its natural habitat is over the continental shelf in the open sea. It is a large fish, growing to over a metre in length. It feeds mainly on other fish according to availability, with shrimps, octopuses and other invertebrates also being eaten. Reproduction takes place throughout most of the year, with the eggs being laid in capsules that adhere to the seabed. The spotback skate is the subject of a fishery and is thought to be overfished, resulting in Greenpeace adding the fish to its red list of fish to be avoided, and the International Union for Conservation of Nature listing it as an "endangered species".
Arhynchobatidae is a family of skates whose members are commonly known as the softnose skates. It belongs to the order Rajiformes in the superorder Batoidea of rays. At least 104 species have been described, in 13 genera. Softnose skates have at times been placed in the same family as hardnose skates, but most recent authors recognize them as a distinct family. Members of the Arhynchobatidae can be distinguished from hardnose skates in having a soft and flexible snout, as well as a more or less reduced rostrum.
Irolita is a genus of softnose skates in the family Arhynchobatidae, commonly known as round skates. There are two species, both endemic to Australia, found over soft bottoms on the outer continental shelves and upper continental slopes, at depths of 50–200 m for the southern round skate and 142–209 m for the western round skate. The distributions of the two species do not overlap.
Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, compose the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.
The mottled skate is a species of skate in the family Rajidae. An inhabitant of shallow coastal waters, it is found in the northwestern Pacific Ocean off Korea, Japan, and China. This species grows to 1.12 m (3.7 ft) long and has a diamond-shaped pectoral fin disc with a long snout. It is characterized by a covering of prickles above and below its snout, but not elsewhere on its body, and a dark ring in the middle of each "wing".
The Korean skate is a skate in the family Rajidae, and is the sole member of the genus Hongeo. It was previously classified in the genus Raja as Raja koreana until discoveries identified this species as a member of a distinct genus. It is considered Critically Endangered on the IUCN Red List due to overexploitation.
Okamejei is a genus of small skates in the family Rajidae from the central and western Indo-Pacific, and the north-western Pacific Ocean.
The clearnose skate is a species of cartilaginous fish in the family Rajidae. R. eglanteria is also known by other common names such as the brier skate and summer skate. Clearnose skates are easily identified by the translucent patches on either side of their snouts and their mottled dorsal surface. They are found along the Atlantic and Gulf coasts of the United States in shallow waters of the continental shelf.
Raja mauritaniensis, commonly known as the African ray, is a species of ray in the family Rajidae. It is found at depths of 50–400 m (160–1,310 ft) in the eastern Atlantic Ocean off Mauritania and Tunisia.
Beringraja rhina, commonly known as the longnose skate, is a species of skate in the family Rajidae from the northeast Pacific. It is found from the eastern Bering Sea and Alaska to Baja California and the Gulf of California. The longnose skate is found at depths of 9–1,069 m (30–3,507 ft) and often deeper than the big skate. The longnose skate has only recently been associated with the genus Beringraja, having been previously included in Raja until genetic evidence supported reclassification. This issue has not be completely resolved and the scientific name "Raja rhina" is still in widespread use.
The Sydney skate is a species of skate of the family Rajidae native to waters off the east coast of Australia.
Rajella fyllae is a species of skate in the family Rajidae.
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