Dwarf sawfish

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Dwarf sawfish
Pristis clavata (Dwarf sawfish) in Aqua park.png
Pristis clavata 2.jpg
Pristis clavata in the Maxell Aqua Park Shinagawa
CITES Appendix I (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Superorder: Batoidea
Order: Rhinopristiformes
Family: Pristidae
Genus: Pristis
Species:
P. clavata
Binomial name
Pristis clavata
Garman, 1906

The dwarf sawfish or Queensland sawfish, Pristis clavata, is a sawfish of the family Pristidae, found in tropical Australia. This endangered species is the smallest species in its family.

Contents

Description

Ventral side of dwarf sawfish Pristis clavata (Dwarf sawfish) in Aqua park shinagawa.png
Ventral side of dwarf sawfish

The dwarf sawfish has a torpedo-shaped body that resembles that of a shark, and grows to a length of about 3.2 m (10.5 ft). It has broad, triangular pectoral fins and large, upright dorsal fins. The first dorsal fin is located directly above, or slightly behind, the origins of the pelvic fins, and the caudal fin has a very small lower lobe. The snout is broad and flat and is elongated into a rostrum with around twenty pairs of rostral teeth. This fish is usually greenish-brown, or occasionally yellowish-brown, on its dorsal surface, and whitish underneath. [3]

Distribution and habitat

The dwarf sawfish is native to the western and central Indo-Pacific region and historically had a much wider range than it does now. Its present confirmed range is from southern New Guinea to the tropical region of northern Australia. [1] A recorded sighting from the Canary Islands was probably of a different species. It typically inhabits inshore waters, estuaries, tidal mudflats and sometimes the lowest reaches of rivers. [4]

Ecology

Dwarf sawfish head Pristis clavata shinagawa aqua stadium.jpg
Dwarf sawfish head

This sawfish feeds mainly on fish, but also eats molluscs and crustaceans. [5] The rostrum has large numbers of pores adapted for electroreception and is probably also used to manipulate prey. Its sensory input helps the fish move about in the muddy waters in which it often lives. [6] Although they are sometimes found in deep water, most movements take place while the tide is either rising or falling, and movements during each tidal cycle may be up to 10 km (6.2 mi). At high tide the fish tend to forage and rest among the mangroves. [3]

Little is known of the breeding habits of the dwarf sawfish. The fish are ovoviviparous with the developing embryos feeding on the yolks of their eggs. It is not known how many young can be carried at one time nor how frequently the fish can breed, but the young are about 65 cm (26 in) long when they are born. Maximum longevity in this species is estimated to be forty-eight years. [3]

Status

The dwarf sawfish is protected in Australian waters, but elsewhere in the world, sawfishes are harvested for their meat, fins, rostrums and oil. The main threat facing the dwarf sawfish is being caught as bycatch in gillnets and trawl nets. That this is the cause of declining numbers is demonstrated by the fact that populations are declining fastest in heavily fished areas. The International Union for Conservation of Nature has assessed the conservation status of this fish as "critically endangered". There is a need for education of fishermen about safe release practices and how to manage their fisheries. However, the threats are continuing, and there is no reason to believe that the population of dwarf sawfish is recovering from previous declines. [1]

Due to the decrease in the number of individuals, this species is rarely stored in aquariums, and as of 2021, 2 individuals (1 male and 1 female) are in captivity in the Japanese public aquarium Aqua Park Shinagawa. [7] [8]

See also

Related Research Articles

<span class="mw-page-title-main">Sawshark</span> Family of fishes

A sawshark or saw shark is a member of a shark order bearing a unique long, saw-like rostrum edged with sharp teeth, which they use to slash and disable their prey. There are eight species within the Pristiophoriformes, including the longnose or common sawshark, shortnose sawshark, Japanese sawshark, Bahamas sawshark, sixgill sawshark, African dwarf sawshark, Lana's sawshark and the tropical sawshark.

<span class="mw-page-title-main">Elasmobranchii</span> Subclass of fishes

Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including 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.

<span class="mw-page-title-main">Sawfish</span> Family of fishes

Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish with some species reaching lengths of about 7–7.6 m (23–25 ft). They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes. All species are endangered.

<span class="mw-page-title-main">Porbeagle</span> Species of shark (Lamna nasus)

The porbeagle or porbeagle shark is a species of mackerel shark in the family Lamnidae, distributed widely in the cold and temperate marine waters of the North Atlantic and Southern Hemisphere. In the North Pacific, its ecological equivalent is the closely related salmon shark (L. ditropis). It typically reaches 2.5 m (8.2 ft) in length and a weight of 135 kg (298 lb); North Atlantic sharks grow larger than Southern Hemisphere sharks and differ in coloration and aspects of life history. Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow base of the tail. It has large pectoral and first dorsal fins, tiny pelvic, second dorsal, and anal fins, and a crescent-shaped caudal fin. The most distinctive features of this species are its three-cusped teeth, the white blotch at the aft base of its first dorsal fin, and the two pairs of lateral keels on its tail.

<span class="mw-page-title-main">Rajiformes</span> Order of fishes in the superorder Batoidea

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.

<span class="mw-page-title-main">Bahamas sawshark</span> Species of shark

The Bahamas sawshark, Pristiophorus schroederi, is a sawshark of the family Pristiophoridae, found in the western Central Atlantic Ocean from the Bahamas and Cuba at depths of between 400 and 1,000 m. These sharks are at least 80 cm long.

<span class="mw-page-title-main">Daggernose shark</span> Species of shark

The daggernose shark is a little-known species of requiem shark, in the family Carcharhinidae, and the only extant member of its genus. It inhabits shallow tropical waters off northeastern South America, from Trinidad to northern Brazil, favoring muddy habitats such as mangroves, estuaries, and river mouths, though it is intolerant of fresh water. A relatively small shark typically reaching 1.5 m (4.9 ft) in length, the daggernose shark is unmistakable for its elongated, flattened, and pointed snout, tiny eyes, and large paddle-shaped pectoral fins.

<span class="mw-page-title-main">Speartooth shark</span> Species of shark

The speartooth shark is a rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5 ft) long.

The narrow sawfish, also known as the pointed sawfish or knifetooth sawfish, is a species of sawfish in the family Pristidae, part of the Batoidea, a superorder of cartilaginous fish that include the rays and skates. Sawfish display a circumglobal distribution in warm marine and freshwater habitats. Their extant biodiversity is limited to five species belonging to two genera. The sawfishes are characterised by the long, narrow, flattened rostrum or extension on their snout. This is lined with sharp transverse teeth, arranged in a way that resembles the teeth of a saw and are used for killing prey. It is found in the shallow coastal waters and estuaries of the Indo-West Pacific, ranging from the Persian Gulf to southern Japan, Papua New Guinea and northern Australia. It is the only living member of the genus Anoxypristis, but was previously included in the genus Pristis. Compared to Pristis, Anoxypristis has a narrower rostral saw with numerous teeth on the distal part and no teeth on the basal one-quarter. It reaches a length of up to 3.5 m (11 ft).

<span class="mw-page-title-main">Largetooth sawfish</span> Species of cartilaginous fish

The largetooth sawfish is a species of sawfish in the family Pristidae. It is found worldwide in tropical and subtropical coastal regions, but also enters freshwater. It has declined drastically and is now critically endangered.

<span class="mw-page-title-main">Smalltooth sawfish</span> Species of cartilaginous fish

The smalltooth sawfish is a species of sawfish in the family Pristidae. It is found in shallow tropical and subtropical waters in coastal and estuarine parts of the Atlantic. Reports from elsewhere are now believed to be misidentifications of other species of sawfish. It is a critically endangered species that has disappeared from much of its historical range.

<span class="mw-page-title-main">Longcomb sawfish</span> Species of cartilaginous fish

The longcomb sawfish, narrowsnout sawfish or green sawfish is a species of sawfish in the family Pristidae, found in tropical and subtropical waters of the Indo-West Pacific. It has declined drastically and is now considered a critically endangered species.

<i>Rhina ancylostoma</i> Species of cartilaginous fish

Rhina ancylostoma, the bowmouth guitarfish, shark ray or mud skate, is a species of ray and a member of the family Rhinidae. Its evolutionary affinities are not fully resolved, though it may be related to true guitarfishes and skates. This rare species occurs widely in the tropical coastal waters of the western Indo-Pacific, at depths of up to 90 m (300 ft). Highly distinctive in appearance, Rhina ancylostoma has a wide and thick body with a rounded snout and large shark-like dorsal and tail fins. Its mouth forms a W-shaped undulating line, and there are multiple thorny ridges over its head and back. It has a dorsal color pattern of many white spots over a bluish gray to brown background, with a pair of prominent black markings over the pectoral fins. This large species can reach a length of 2.7 m (8.9 ft) and weight of 135 kg (298 lb).

<i>Pristis</i> Genus of cartilaginous fishes


Pristis is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and all species are considered critically endangered today.

<span class="mw-page-title-main">Batoidea</span> Superorder of cartilaginous fishes

Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, comprise 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.

<span class="mw-page-title-main">Memorandum of Understanding on the Conservation of Migratory Sharks</span>

The Memorandum of Understanding on the Conservation of Migratory Sharks is an international instrument for the conservation of migratory species of sharks. It was founded under the auspices of the Convention on the Conservation of Migratory Species of Wild Animals.

<span class="mw-page-title-main">Aqua Park Shinagawa</span> Aquarium in Shinagawa Prince Hotel, Tokyo

Maxell Aqua Park Shinagawa, formerly Epson Aqua Park Shinagawa, Epson Shinagawa Aqua Stadium is a public aquarium located inside the Shinagawa Prince Hotel in Minato, Tokyo. It can be accessed from Shinagawa Station.

References

  1. 1 2 3 Grant, M.I.; Charles, R.; Fordham, S.; Harry, A.V.; Lear, K.O.; Morgan, D.L.; Phillips, N.M.; Simeon, B.; Wakhida, Y.; Wueringer, B.E. (2022). "Pristis clavata". IUCN Red List of Threatened Species . 2022: e.T39390A68641215. doi: 10.2305/IUCN.UK.2022-2.RLTS.T39390A68641215.en . Retrieved 9 December 2022.
  2. "CITES Appendices I, II and III" (PDF). Convention on International Trade in Endangered Species of Wild Fauna and Flora. 4 May 2023. p. 54. Retrieved 20 May 2023.
  3. 1 2 3 Curtis, Lee K.; Dennis, Andrew J.; McDonald, Keith R. (2012). Queensland's Threatened Animals. Csiro Publishing. pp. 82–. ISBN   978-0-643-09614-1.
  4. Garilao, Cristina V. "Pristis clavata". FishBase. Retrieved 2015-08-19.
  5. "Dwarf Sawfish (Pristis clavata)". NOAA Fisheries. 2014-12-16. Retrieved 2015-08-19.
  6. Wueringer B.E.; Peverell S.C.; Seymour J.; Squire Jr. L.; Kajiura S.M.; Collin S.P. (2011). "Sensory Systems in Sawfishes. 1. The Ampullae of Lorenzini". Brain, Behavior and Evolution. 78 (2): 130–149. doi:10.1159/000329515. PMID   21829004. S2CID   16357946.
  7. ""裏の顔"が人気!ノコギリエイの展示は3水族館のみ。性格・特徴、世界唯一展示も". るるぶkids (in Japanese). 13 September 2020. Retrieved 20 May 2023.
  8. "Guide to the facility UPPER FLOOR (2F) | Maxell Aqua Park Shinagawa". Maxell Aqua Park Shinagawa. Archived from the original on 5 October 2020.