The graceful shark or Queensland shark (''Carcharhinus amblyrhynchoides'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of requiem shark, in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Carcharhinidae, found in the

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

, from the

Gulf of Aden The Gulf of Aden (; ) is a deepwater gulf of the Indian Ocean between Yemen to the north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel, the Socotra Archipelago, Puntland in Somalia and Somaliland to the south. ...

northern Australia The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26th parallel south, 26° and all of the Northern Territory. Those local government areas of Western Australia and Q ...

. It is a midwater species that has been recorded to a depth of . A stoutly built shark growing up to long, the graceful shark has a short, wedge-shaped snout, large, sickle-shaped

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s and first

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, and black tips on most fins. Graceful sharks prey mainly on

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

es, and to a much lesser extent on

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s and

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s. It is

viviparous In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juve ...

, with females bearing litters of up to 9 pups following a 9- to 10-month

gestation period In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once i ...

. Off northern Australia, birthing occurs in January and February, with

mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...

shortly after. This species is potentially dangerous, but has not been implicated in any attacks. It is caught incidentally by

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often p ...

throughout its range for meat, fins, and liver oil, though specific information is lacking. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

has listed it under

Near Threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

Taxonomy and phylogeny

Australian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Gilbert Percy Whitley Gilbert Percy Whitley (9 June 1903 – 18 July 1975) was a British-born Australian ichthyologist and malacologist who was curator of fishes at the Australian Museum in Sydney for about 40 years. Early life and education Gilbert Percy Whitley ...

originally described the graceful shark as ''Gillisqualus amblyrhynchoides'', in a 1934 issue of ''Memoirs of the Queensland Museum''. He based his account on a 60-cm-long immature female caught off Cape Bowling Green in

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

, hence the alternate

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

Queensland shark. Later authors have synonymised ''Gillisqualus'' with ''Carcharhinus''. As with most ''Carcharhinus'' species, the evolutionary relationships of the graceful shark are poorly resolved. Based on

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

Jack Garrick John Andrew Frank Garrick (24 March 1928 – 30 August 2018) was a New Zealand ichthyologist. Career Garrick specialised in elasmobranchs and published many books and articles about shark and ray biology. In 1982, he published a thorough taxonom ...

concluded in 1982 that its closest relative was the

blacktip shark The blacktip shark (''Carcharhinus limbatus'') is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have ...

(''C. limbatus''), and that the two were closely related to the

spinner shark The spinner shark (''Carcharhinus brevipinna'') is a type of requiem shark, in the family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwid ...

(''C. brevipinna''). Leonard Compagno, in his 1988

phenetic In biology, phenetics (; ), also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually with respect to Morphology (biology), morphology or other observable traits, regardless of their phylogeny or evoluti ...

study, also grouped those species together, along with the smoothtooth blacktip shark (''C. leiodon'') and the finetooth shark (''C. isodon''). However,

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

techniques have since found this interpretation to be invalid for the spinner, blacktip, and finetooth sharks.

Distribution and habitat

The graceful shark is distributed widely in the tropical Indo-Pacific, having been reported from the Gulf of Aden, southwestern India and Sri Lanka, the

Gulf of Thailand The Gulf of Thailand (), historically known as the Gulf of Siam (), is a shallow inlet adjacent to the southwestern South China Sea, bounded between the southwestern shores of the Indochinese Peninsula and the northern half of the Malay Peninsula. ...

, Vietnam, the Philippines to

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

and

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

, and

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

to northern Australia from

Townsville The City of Townsville is a city on the north-eastern coast of Queensland, Australia. With a population of 201,313 as of 2024, it is the largest settlement in North Queensland and Northern Australia (specifically, the parts of Australia north of ...

to Eighty Mile Beach. Given its rarity and the difficulty in distinguishing it from related species, its range is probably continuous and wider than the present patchy records suggest. The graceful shark is an open-water inhabitant that can be found from close to shore to the outer continental and insular shelves, diving at least .

Description

Contrary to its common name, the graceful shark's spindle-shaped body has been described as "tubby". The wedge-like snout is short and pointed. The eyes are rather large and circular, and equipped with

nictitating membrane The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. Most ...

s (protective third eyelids). The mouth has short, indistinct furrows at the corners and contains 31–33 upper and 29–33 lower tooth rows. The upper teeth have a single narrow cusp with serrated edges, upright at the center of the jaw and becoming more oblique on the sides. The lower teeth are similar to the upper teeth, but more upright and slender. The five pairs of

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In c ...

s are fairly long. The

s are falcate (sickle-shaped) and taper to pointed tips; their leading margins measure about a fifth as long as the total length in sharks over long. The first

is high and broad, with a pointed apex and a concave trailing margin; its origin lies roughly over the insertion (the rear of the fin base) of the pectoral fins. The second dorsal fin is relatively large and located about opposite the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

, which is about of equal size. There is no ridge between the dorsal fins. The

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

has a well-developed lower lobe and a ventral notch near the tip of the upper lobe. This species is bronze above and white below, which extends onto the flanks as a pale stripe. The pectoral fins, dorsal fins, lower caudal fin lobe, and sometimes the pelvic fins usually have black tips, while the upper caudal fin lobe darkens towards the trailing edge and the anal fin may be completely light. The fin markings tend to fade with age. The maximum known length is .

Biology and ecology

The graceful shark feeds predominantly on

es, with

s and

s being of minor importance. Jacks make up over 60% of its fish diet in the

Gulf of Carpentaria The Gulf of Carpentaria is a sea off the northern coast of Australia. It is enclosed on three sides by northern Australia and bounded on the north by the eastern Arafura Sea, which separates Australia and New Guinea. The northern boundary ...

. Like other members of its family, this species is

: once the developing

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

s exhaust their supply of

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

, the depleted

yolk sac The yolk sac is a membranous wikt:sac, sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac' ...

is converted into a

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

l connection to the mother. Off northern Australia, males and females likely mate every year in February, with

ovulation Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...

following shortly after. Females typically bear litters of three, though individuals gestating up to 9 pups have been reported. The young are born in January or February, following a

of 9–10 months.

Sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...

is attained at a length of for both sexes. A known

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

of this species is a tapeworm in the genus ''Cathetocephalus''.

Human interactions

Given its size, the graceful shark is potentially dangerous to humans, though no attacks have been recorded. It is caught incidentally by

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

, and probably elsewhere, using

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s and longlines. It is a minor component of shark catches off northern Australia, comprising around 1.5% and 0.2% of all sharks caught in gillnets and on longlines, respectively, in the mid-1980s. Catches in the region have declined from historical highs in the 1970s and 1980s due to the departure of foreign fishing vessels following new gillnet regulations. The meat is sold fresh or dried and salted, the fins are shipped to

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

for

shark fin soup Shark's fin soup is a soup or stewed dish served in parts of China, Taiwan, and Southeast Asia. The shark fins provide texture, while the taste comes from the other ingredients. It is commonly served at special occasions such as weddings and ba ...

, and the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

is processed for

vitamin Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...

s. The

has assessed this species as

, noting more biological and fishery information is needed.

References

External links

Species Description of Carcharhinus amblyrhynchoides at www.shark-references.com
{{Taxonbar, from=Q135369 graceful shark graceful shark