Dwarf sawtail catshark

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Dwarf sawtail catshark
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Scyliorhinidae
Genus: Galeus
Species:
G. schultzi
Binomial name
Galeus schultzi
Galeus schultzi distmap.png
Range of the dwarf sawtail catshark

The dwarf sawtail catshark (Galeus schultzi) is a little-known species of catshark, belonging to the family Scyliorhinidae, found exclusively in the deep waters off Luzon in the Philippines. Unlike other members of its genus, this slender, diminutive shark has a short, rounded snout and very short furrows at the corners of its jaws. It has indistinct darker saddles beneath each dorsal fin and two dark bands on the caudal fin, as well as a prominent crest of enlarged dermal denticles along the upper caudal fin margin.

Contents

Taxonomy

Renowned shark expert Stewart Springer described the dwarf sawtail catshark in a 1979 National Oceanic and Atmospheric Administration (NOAA) Technical Report. The type specimen is an adult male 30 cm (12 in) long, collected from Balayan Bay. [2] It does not closely resemble more typical Galeus species, and its placement within the genus is not concrete. [3]

Distribution and habitat

The dwarf sawtail catshark is endemic to Luzon in the Philippines. It is found on or near the bottom over the upper continental slope at a depth of 329–431 m (1,079–1,414 ft), barring a single record from a depth of 50 m (160 ft) on the outer continental shelf. [1]

Description

Reaching a length of 30 cm (12 in), [1] the dwarf sawtail catshark has a slim, firm body and a distinctively short, rounded snout. The nostrils are divided by triangular flaps of skin on their anterior rims. The horizontally oval eyes are placed somewhat high on the head, and equipped with rudimentary nictitating membranes (protective third eyelids). There are low ridges beneath the eyes, and tiny spiracles behind them. The large, wide, arched mouth bears very short furrows at the corners. [4] There are 48 tooth rows in the upper jaw, and fewer in the lower jaw; each tooth has a narrow central cusp flanked by lateral cusplets. There are five pairs of gill slits. [3]

The two dorsal fins have rounded apexes and are similar in size; the first originates over the aft portion of the pelvic fins, and the second over the aft portion of the anal fin. The pectoral fins are large and wide. The pelvic and anal fins are short and low, with angular corners. The base of the anal fin measures 1011% of the total length, longer than the distances between either the dorsal fins or the pelvic and anal fins. The caudal peduncle is nearly cylindrical and leads to a low caudal fin with an indistinct lower lobe and a ventral notch near the tip of the upper lobe. [4] The small, overlapping dermal denticles each have a leaf-shaped crown with a median ridge and three teeth on the posterior margin. A crest of enlarged denticles is present along the dorsal caudal fin margin. [3] This species is brownish above and lighter below, with a faint darker saddle beneath each dorsal fin, and two darker bands on the caudal fin. The interior of the mouth varies from light to dusky. [4]

Biology and ecology

The natural history of the dwarf sawtail catshark is poorly known. Males attain sexual maturity at around 25 cm (9.8 in) long, and females at 27–30 cm (11–12 in) long. [1]

Human interactions

Only a few specimens of the dwarf sawtail catshark have been collected. The International Union for Conservation of Nature (IUCN) to list this species as least concern. The depth range it occupies is not known to be utilized by commercial trawl fisheries. [1]

Related Research Articles

<i>Galeus</i> Genus of sharks

Galeus is a genus of catshark, belonging to the family Scyliorhinidae, commonly known as sawtail catsharks in reference to a distinctive saw-toothed crest of enlarged dermal denticles, found along the upper edges of their caudal fins. They are found in the Atlantic, the western and central Pacific, and the Gulf of California, inhabiting deep waters at or close to the sea floor. Members of this genus are rather small, slim sharks with firm bodies and thick, rough skin. Their heads are usually fairly long and pointed, and have large mouths with well-developed furrows at the corners. They have large pectoral and anal fins, and two similar dorsal fins placed well back. Many species are ornately patterned with dark saddles and/or blotches. Sawtail catsharks feed on various invertebrates and fishes, and may be either egg-laying or live-bearing. These harmless sharks are sometimes caught as bycatch but are of minimal commercial value.

Antilles catshark Species of shark

The Antilles catshark is a common but little-known species of catshark, part of the family Scyliorhinidae. It is found on or near the bottom at a depth of 293–695 m (961–2,280 ft) off Florida and the West Indies from Jamaica to Martinique. It was once regarded as a subspecies of the similar roughtail catshark, along with the longfin sawtail catshark. Growing to 46 cm (18 in) long, the Antilles catshark is a slender species with a marbled color pattern of dark saddles and blotches, as well as a crest of enlarge dermal denticles along the front part of its dorsal caudal fin margin. It feeds on shrimp and may have schooling habits. Reproduction is oviparous.

Atlantic sawtail catshark Species of shark

The Atlantic sawtail catshark is a little-known species of catshark, part of the family Scyliorhinidae, found in a small area of the northeastern Atlantic Ocean, centered on the Strait of Gibraltar and the Alborán Sea. It is found on or close to the bottom over the continental slope, mostly at depths of 400–600 m (1,300–2,000 ft). This shark closely resembles, and was once thought to be the same species as, the blackmouth catshark ; both are slender with a series of dark saddles and blotches along the back and tail, and a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin. It differs subtly from G. melastomus in characters including snout length, caudal peduncle depth, and the color of the furrows at the corner of its mouth.

Roughtail catshark Species of shark

The roughtail catshark or marbled catshark is a common species of catshark, part of the family Scyliorhinidae. It is found at a depth of 36–702 m (118–2,303 ft) in the northwestern Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea, from North Carolina to Costa Rica. Individuals of different sexes and ages are segregated to some degree. A small species not exceeding 33 cm (13 in) in length, the roughtail catshark has a slender body with a marbled color pattern of dark saddles and spots, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. This species feeds mainly on shrimp and is oviparous. It is caught incidentally in shrimp trawls, though trawl fisheries within its range mostly do not operate at the depths it inhabits. As a result, the International Union for Conservation of Nature has listed it under Least Concern.

Australian sawtail catshark Species of shark

The Australian sawtail catshark is a common species of catshark, and part of the family Scyliorhinidae, endemic to southern Australian waters. It is found on or near the bottom of the outer continental shelf and upper continental slope, at depths of 85 to 823 m. This slim-bodied species is characterized by crests of enlarged dermal denticles along both the dorsal and ventral edges of its caudal fin and caudal peduncle, along with a color pattern of broad, dark saddles outlined in white. It can grow to 61 cm (24 in) in length. The Australian sawtail catshark feeds mainly on fishes, crustaceans, and cephalopods. Females are oviparous and lay eggs enclosed by capsules. This species is often caught incidentally by commercial bottom trawl fisheries, but is not significantly threatened by fishing activity. Thus, it has been assessed as of Least Concern by the International Union for Conservation of Nature (IUCN).

Longfin sawtail catshark Species of shark

The longfin sawtail catshark is a rare, little-known species of catshark, part of the family Scyliorhinidae. Once thought to be a subspecies of the roughtail catshark along with the Antilles catshark, it inhabits deep water off the Caribbean coasts of Panama and Colombia. This slim-bodied species has a marbled dorsal color pattern and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. It can be distinguished from similar species by its relatively longer anal fin and small adult length of under 35 cm (14 in). The longfin sawtail catshark is oviparous.

Gecko catshark Species of shark

The gecko catshark is a species of catshark, part of the family Scyliorhinidae, native to the northwestern Pacific Ocean from southern Japan to Taiwan, and possibly also off Vietnam. It is a common, demersal species found at depths of 100–900 m (330–2,950 ft). Its body is slender, with a pattern of dark saddles and blotches. The dorsal and caudal fins are edged in white, and there is a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin. The gecko catshark is a schooling, opportunistic predator of bony fishes, cephalopods, and crustaceans. It is oviparous, with females producing two vase-shaped egg capsules at a time. This species is captured as bycatch, but does not appear to be threatened by fishery activities at present and has been assessed as Least Concern by the International Union for Conservation of Nature (IUCN).

Slender sawtail catshark Species of shark

The slender sawtail catshark is a little-known species of catshark, part of the family Scyliorhinidae, endemic to northern Australia. It is found over the continental slope in 290–470 m (950–1,540 ft) on water. Growing to 34 cm (13 in) long, this shark has a slim gray body with four dark saddle markings below the dorsal fins and on the caudal fin, as well as a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin. The slender sawtail catshark is not valued by fisheries but is taken as bycatch. The International Union for Conservation of Nature (IUCN) presently lacks enough information to assess its conservation status.

Longnose sawtail catshark Species of shark

The longnose sawtail catshark is a little-known species of catshark, part of the family Scyliorhinidae, found off the northwestern Pacific islands of Amami Ōshima, Ogasawara, and Izu at depths of 350–550 m (1,150–1,800 ft). Reaching a length of 80 cm (31 in), it is characterized by a long flattened snout, a long space between the pelvic and anal fins, and a crest of enlarged dermal denticles along the dorsal caudal fin edge. Adults are plain dark gray above, while juveniles have a few faint dark saddles on the back and tail.

Southern sawtail catshark Species of shark

The southern sawtail catshark is a species of catshark, part of the family Scyliorhinidae, endemic to southern Brazil. It inhabits deepwater reefs on the upper continental slope at a depth of 236–600 m (774–1,969 ft). Reaching at least 43 cm (17 in) in length, this slim-bodied species closely resembles the Antilles catshark. It has a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin, as well as a distinctive color pattern of dark oval blotches, outlined in white, along its back. The southern sawtail catshark is oviparous, with females producing reddish egg capsules. The International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable; it is often taken as bycatch and may be threatened by intensifying squid fishing.

Mouse catshark Species of shark

The mouse catshark is a species of catshark and part of the family Scyliorhinidae. It is common in the northeastern Atlantic Ocean from Iceland to Western Sahara. There is much taxonomic confusion regarding this species in Icelandic waters, where it may be confounded with another species of Galeus or Apristurus. Probably not exceeding 49 cm (19 in) long, the mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins. In addition, in adult males the inner margins of the pelvic fins are merged into an "apron".

Broadfin sawtail catshark Species of shark

The broadfin sawtail catshark is a common species of catshark, part of the family Scyliorhinidae. It is found on or near the bottom at depths of 150–540 m (490–1,770 ft), from southeastern Japan to the East China Sea. A slender species growing to 68 cm (27 in) long, this shark is characterized by a fairly long, pointed snout, a series of indistinct, dark saddles along its back and tail, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. In addition, adult males have very long claspers that reach past the anal fin. The broadfin sawtail catshark is an opportunistic predator of bony fishes, cephalopods, and crustaceans, with immature and mature sharks being primarily piscivorous. It is oviparous and reproduces year-round.

Peppered catshark Species of shark

The peppered catshark is a common but little-known species of catshark, part of the family Scyliorhinidae, inhabiting depths of 130–1,326 m (427–4,350 ft) in the northern Gulf of California. It is found on or near the ocean floor, and conducts seasonal migrations, spending winter in deeper water. Reaching a length of 37 cm (15 in), this species has a slender grayish body with a fine covering of black dots. On the dorsal edge of its caudal fin is a prominent crest of enlarged dermal denticles. It is oviparous, with the reproductive period probably lasting from May to September. The International Union for Conservation of Nature (IUCN) has listed the peppered catshark under Least Concern, as it faces no significant threats from human activity.

African sawtail catshark Species of shark

The African sawtail catshark is a species of catshark, part of the family Scyliorhinidae. Demersal in nature, it is found at depths of 160–720 m (520–2,360 ft) off the western African coast from Morocco to South Africa. This slender species has a rather long, pointed snout, a series of dark saddles along the back and tail, and a prominent crest of enlarged dermal denticles along the upper edge of the caudal fin. Its maximum known length is 46 cm (18 in).

Blacktip sawtail catshark Species of shark

The blacktip sawtail catshark is a species of catshark, and part of the family Scyliorhinidae, found off the coasts of Taiwan and the Philippines. It is demersal in nature and occurs deeper than 60 m (200 ft). Growing up to 46 cm (18 in) long, this slim-bodied species is characterized by its plain brownish dorsal coloration with dark tips on the dorsal and caudal fins, and a prominent crest of enlarged dermal denticles on the upper edge of the caudal fin. It is oviparous, with females producing encapsulated eggs two at a time year-round. The blacktip sawtail catshark is caught incidentally in bottom trawls and used for fishmeal in Taiwan.

Springers sawtail catshark Species of shark

Springer's sawtail catshark is a little-known species of catshark, belonging to the family Scyliorhinidae, found in waters 457–699 m (1,499–2,293 ft) deep off the islands of the Antilles, from Cuba to the Leewards. A small, slim-bodied species reaching a length of 48 cm (19 in), the Springer's sawtail catshark can be identified by its color pattern of horizontal dark stripes in front of the first dorsal fin, and dark dorsal saddles behind. It is additionally characterized by the presence of saw-toothed crests, made of enlarged dermal denticles along both the dorsal and the ventral edges of the caudal fin. The Springer's sawtail catshark is oviparous.

Northern sawtail catshark Species of shark

The northern sawtail catshark is a little-known species of catshark, and part of the family Scyliorhinidae, endemic to northeastern Australia. It is demersal in nature and inhabits the upper continental slope at a depth of 300–420 m (980–1,380 ft). A small, slender species growing no longer than 42 cm (17 in), the northern sawtail catshark is characterized by a series of dark, narrow saddles along its back and tail, and rows of prominently enlarged dermal denticles along the upper edge of its caudal fin and the underside of its caudal peduncle. The International Union for Conservation of Nature (IUCN) does not yet have enough information to assess its conservation status.

Natal shyshark Species of shark

The Natal shyshark, eastern shyshark or happy chappie is a species of catshark, belonging to the family Scyliorhinidae. It was once regarded as the "Natal" form of the puffadder shyshark. This shark is endemic to a small area off South Africa from the Western Cape to KwaZulu-Natal. It is found close to the coast, from the surf zone to a depth of 30 m (98 ft), and has benthic habits. Reaching 50 cm (20 in) in length, the Natal shyshark is similar to the puffadder shyshark in appearance but has a stockier body, less flattened head, a compressed caudal peduncle, and a different color pattern. Rare and under threat from habitat degradation and commercial fishing, it has been assessed as Vulnerable by the International Union for Conservation of Nature (IUCN).

Figaro is a genus of catshark, and part of the family Scyliorhinidae. Until 2008, Figaro was generally considered to be a subgenus of Galeus. The two known species are found off Australia, inhabiting deep, offshore waters on or near the bottom. Figaro contains small, slender, firm-bodied sharks that bear distinctive crests of enlarged, spiny dermal denticles along the dorsal and ventral edges of their short caudal fins. The caudal peduncle is relatively long, such as that the anal and caudal fins are some distance apart. In adult males, the inner margins of the pelvic fins are fused together to form a subtle "apron" over the claspers. F. boardmani is a predator of fishes, crustaceans, and cephalopods, and is oviparous; less is known about the F. striatus. Both are harmless and are of no economic importance.

The phallic catshark is a little-known species of catshark, belonging to the family Scyliorhinidae. It is found on or near the ocean floor, in the deep waters off New Caledonia and Vanuatu. A slender species attaining a length of 46 cm (18 in), it is characterized by a long caudal fin bearing a crest of enlarged dermal denticles along the dorsal margin, and very long claspers in adult males. This shark is gray-colored, with four dark saddles along the back and tail.

References

  1. 1 2 3 4 5 Dulvy, N.K., Bineesh, K.K., Cheok, J., Sherman, C.S. & VanderWright, J. (2020). "Galeus schultzi". IUCN Red List of Threatened Species . 2020: e.T161333A124467078.CS1 maint: multiple names: authors list (link)
  2. Springer, S. (April 1979). A revision of the catsharks, family Scyliorhinidae. NOAA Technical Report NMFS Circular No. 422: 115
  3. 1 2 3 Compagno, L.J.V. (1988). Sharks of the Order Carcharhiniformes. Blackburn Press. pp. 134–142, 433. ISBN   1-930665-76-8.
  4. 1 2 3 Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Food and Agricultural Organization. p. 318. ISBN   92-5-101384-5.