The hardnose shark (''Carcharhinus macloti'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

requiem shark Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) and include such species as the tiger shark, bull shark, le ...

, in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Carcharhinidae, so named because of the heavily

calcified Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature Mat ...

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

s in its snout. A small bronze-coloured shark reaching a length of , it has a slender body and a long, pointed snout. Its two modestly sized

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s have distinctively elongated rear tips. The hardnose shark is widely distributed in the western

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 Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore. Common and gregarious, the hardnose shark is a

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

es,

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

s, and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. This species is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

, with the growing

embryo An embryo is an initial stage of development of 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 spe ...

s sustained to term via a

placenta The placenta 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 the physically separate mater ...

l connection to their mother. Females have a biennial reproductive cycle and bear litters of one or two pups after a twelve-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 it ...

. The hardnose shark is fished for meat throughout its range and, given its low reproductive rate, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) has listed it as

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

Taxonomy

The hardnose shark was described by German biologists Johannes Müller and

Jakob Henle Friedrich Gustav Jakob Henle (; 9 July 1809 – 13 May 1885) was a German physician, pathologist, and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay, "On Miasma and Contagia," was an early argument for ...

in their 1839 ''Systematische Beschreibung der Plagiostomen''. They named it ''Carcharias (Hypoprion) macloti'' in honour of

Heinrich Christian Macklot Heinrich Christian Macklot (20 October 1799, Frankfurt am Main – 12 May 1832) was a German naturalist. He studied medicine at the University of Heidelberg, earning his doctorate in 1822. Later that year, he found employment at the Rijksm ...

, who collected the

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

from

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

. In 1862, American ichthyologist

Theodore Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural histor ...

elevated ''Hypoprion'' to the rank of full genus, with ''C. macloti'' as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

. In 1985,

Jack Garrick John Andrew Frank "Jack" Garrick (1928 – August 30, 2018) was a New Zealand ichthyologist. He specialized in elasmobranchs and published many books and articles about shark and ray biology. In 1982, he published a thorough taxonomy on sharks of ...

synonymised ''Hypoprion'' with ''

Carcharhinus ''Carcharhinus'' is the type genus of the family Carcharhinidae, the requiem sharks. One of 12 genera in its family, it contains over half of the species therein. It contains 35 extant and eight extinct species to date, with likely more species y ...

''. This species may also be called Maclot's shark.

Phylogeny and evolution

The evolutionary relationships of the hardnose shark have not been fully resolved. In a 1988 study 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, ...

Leonard Compagno Leonard Joseph Victor Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organi ...

tentatively grouped the hardnose shark with the

Borneo shark The Borneo shark (''Carcharhinus borneensis'') is a species of requiem shark, and part of the family Carcharhinidae. Extremely rare, it is known only from inshore waters around Mukah in northwestern Borneo, though it may once have been more wi ...

(''C. borneensis''),

whitecheek shark The whitecheek shark or widemouth blackspot shark (''Carcharhinus dussumieri'') is a requiem shark of the family Carcharhinidae, found in the Indo-West Pacific Ocean between latitudes 34°N and 25°S. It can reach a length of 1 m. It feed ...

(''C. dussumieri''),

Pondicherry shark The Pondicherry shark (''Carcharhinus hemiodon'') is an extremely rare species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than and has a fairly long, pointed snout. This species can be ...

(''C. hemiodon''), creek whaler (''C. fitzroyensis''),

smalltail shark The smalltail shark (''Carcharhinus porosus'') is a species of requiem shark, and part of the family Carcharhinidae. It is found in the western Atlantic Ocean, from the northern Gulf of Mexico to southern Brazil. It inhabits shallow waters close ...

(''C. porosus''),

blackspot shark The blackspot shark (''Carcharhinus sealei'') is a small species of requiem shark in the family Carcharhinidae found in the tropical Indo-West Pacific Ocean between latitudes 24°N and 30°S, from the surface to a depth around . Its length is ...

(''C. sealei''), and

spottail shark The spot-tail shark, or sorrah shark (''Carcharhinus sorrah''), is a species of requiem shark, in the family Carcharhinidae, found in the tropical Indo-West Pacific Ocean between latitudes 31°N and 31°S, from the surface to a depth around . ...

(''C. sorrah''). Results from

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 ...

analyses have been inconsistent, with some supporting parts of Compagno's

hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

: a 1992 study could not resolve the hardnose shark's position in detail, a 2011 study reported that it was close to the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

formed by the whitecheek and blackspot sharks, and a 2012 study concluded that it was the

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

of the Borneo shark. Teeth apparently belonging to the hardnose shark have been recovered from the Pungo River and Yorktown Formations in the United States, and from the Pirabas Formation in Brazil. The earliest of these

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s date to the

Lower Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

(23–16 Ma).

Description

The hardnose shark is a slim-bodied species with a long, narrow, and pointed snout. Unlike in other ''Carcharhinus'' species, its rostral (snout)

s are highly

, hence the name "hardnose". The circular eyes are rather large and equipped with protective

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. All ...

s. There is a narrow lobe of skin on the anterior rim of each nostril. The arched mouth bears inconspicuous furrows at the corners; some sources report that the hyomandibular pores (a series of pores above the corners of the mouth) are enlarged, while others report that they are not. The upper teeth number 29–32 rows and have a narrow, smooth-edged central cusp with very coarse serrations at the base on either side. The lower teeth number 26–29 rows and are narrow and smooth-edged. There are five pairs of fairly short

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 con ...

s. The

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s are fairly short and pointed, with a falcate (sickle-like) shape. The first

is medium-sized and triangular, and originates roughly over the pectoral fin free rear tips. The second dorsal fin is small and low, and originates over the middle of the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

base. Both dorsal fins have very long free rear tips, and there is a subtle midline ridge between them. A prominent notch is present on the

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

at the dorsal origin of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. The caudal fin has a well-developed lower lobe and a longer upper lobe with a ventral notch near the tip. The skin is covered by overlapping, oval-shaped

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s; each denticle has three horizontal ridges leading to marginal teeth. This species is bronze above and white below, with a barely noticeable pale band on the flanks. The pectoral,

pelvic The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

, and anal fins sometimes have lighter margins, while the first dorsal fin and upper caudal fin lobe may have darker margins. The hardnose shark reaches in length.

Distribution and habitat

The hardnose shark is common and widely distributed in the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

western

. It is found from Kenya to Myanmar in the Indian Ocean, including Sri Lanka and the

Andaman Islands The Andaman Islands () are an archipelago in the northeastern Indian Ocean about southwest off the coasts of Myanmar's Ayeyarwady Region. Together with the Nicobar Islands to their south, the Andamans serve as a maritime boundary between th ...

. In the Pacific Ocean, it is found from Vietnam to

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

and southern Japan, in Indonesia, and off New Guinea and northern Australia. It is usually found in shallow,

inshore A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past a ...

waters, but has been reported to a depth of . Tagging data has shown that this shark tends not to make long-distance movements, with 30% of re-caught individuals having moved less than from their initial tagging location. The longest known distance travelled by an individual is .

Biology and ecology

The hardnose shark forms large groups, often associating with spottail sharks and

Australian blacktip shark The Australian blacktip shark (''Carcharhinus tilstoni'') is a species of requiem shark, in the family Carcharhinidae, endemic to northern and eastern Australia. Favoring the upper and middle parts of the water column, it can be found from the i ...

s (''C. tilstoni''). Males and females generally roam separately from each other.

Bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

es form the main part of this shark's diet, with

s and

s making up the remainder.

Parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s of this species include the

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

'' Acanthocheilus rotundatus'' and the

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...

'' Otobothrium carcharidis''. The hardnose shark is

; like in other requiem sharks, once the

s exhaust their

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 ...

supply, the empty yolk sac develops into a

l connection through which the mother provides nutrition. Females give birth once every other year to one or two pups, following a

of twelve months. Newborns measure long, and

sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitio ...

is attained at long. The

maximum lifespan Maximum life span (or, for humans, maximum reported age at death) is a measure of the maximum amount of time one or more members of a population have been observed to survive between birth and death. The term can also denote an estimate of the maxi ...

is at least 15–20 years.

Human interactions

Harmless to humans, the hardnose shark is caught with

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 line gear by

artisanal An artisan (from french: artisan, it, artigiano) is a skilled craft worker who makes or creates material objects partly or entirely by hand. These objects may be functional or strictly decorative, for example furniture, decorative art, s ...

and

commercial Commercial may refer to: * a dose of advertising conveyed through media (such as - for example - radio or television) ** Radio advertisement ** Television advertisement * (adjective for:) commerce, a system of voluntary exchange of products and s ...

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

across much of its range. It is used for meat, which is sold fresh or dried and salted, though its small size limits its economic importance. Its low reproductive rate may render it susceptible to

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

, and given existing levels of exploitation, the

(IUCN) has assessed it as

. Off northern Australia, the hardnose shark makes up 13.6% of the gillnet catch and 4.0% of the

longline Long line or longline may refer to: *''Long Line'', an album by Peter Wolf *Long line (topology), or Alexandroff line, a topological space *Long line (telecommunications), a transmission line in a long-distance communications network *Longline fish ...

catch. Since these losses do not appear to have diminished its population there, the IUCN has given it a regional assessment of

Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

References

External links

"''Carcharhinus macloti'', Hardnose shark" at FishBase"Species description of ''Carcharhinus macloti''" at Shark-References.com
{{Taxonbar, from=Q1587674 Carcharhinus Fish described in 1839