The hedgehog seahorse (''Hippocampus spinosissimus'') is a species of fish of the family

Syngnathidae The Syngnathidae is a family of fish which includes seahorses, pipefishes, and seadragons (''Phycodurus'' and '' Phyllopteryx''). The name is derived from grc, σύν (), meaning "together", and (), meaning "jaw". The fused jaw is one of the t ...

. It inhabits coastal waters from

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

and Sri Lanka 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 northern Australia. It is threatened by overfishing, as both targeted catch and bycatch. This species is

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

, with males carrying eggs in a brood pouch before giving birth to live young.Lourie, S.A., A.C.J. Vincent and H.J. Hall, 1999. Seahorses: an identification guide to the world's species and their conservation. Project Seahorse, London. p. 214

Identification

''Hippocampus spinosissimus'' is usually around long, with a long snout and a low

coronet A coronet is a small crown consisting of ornaments fixed on a metal ring. A coronet differs from other kinds of crowns in that a coronet never has arches, and from a tiara in that a coronet completely encircles the head, while a tiara doe ...

. Spines vary through life, with juveniles being more spiny than adults. Individuals usually have a yellow-orange to deep red or dark brown snout, a dark front of head, and pale grey saddles or bands over the trunk and tail. Deepwater specimens are usually red or orange, likely to match the sponges and

corals Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secr ...

at that depth.Dianne J. Bray & Vanessa J. Thompson, Hippocampus spinosissimus in Fishes of Australia, accessed 17 Mar 2018, http://fishesofaustralia.net.au/home/species/1549

Habitat

''Hippocampus spinosissimus'' inhabits

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock o ...

systems, occupying sand or

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...

bottoms, to a maximum depth of . In the central

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, individuals are most commonly found on relatively barren soft or sandy bottoms and depressions, where they associate with

octocorals Octocorallia (also known as Alcyonaria) is a class of Anthozoa comprising around 3,000 species of water-based organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fan ...

sea stars Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ar ...

sea pens Sea pens are colonial marine cnidarians belonging to the order Pennatulacea. There are 14 families within the order; 35 extant genera, and it is estimated that of 450 described species, around 200 are valid. Sea pens have a cosm ...

sea urchins Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

, sponges, submerged wood and

macroalgae Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as k ...

. They are rarely found in direct association with

reefs A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes—deposition of sand, wave erosion planing down rock out ...

or hard

. Trawls in Malaysia indicate similar habitat choice.

Ecology

Feeding

This species is

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

, feeding on small

crustaceans 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 ...

such as copepods,

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

, and

gammarid Gammaridae is a family of amphipods. In North America they are included among the folk taxonomic category of " scuds", and otherwise gammarids is usually used as a common name. They have a wide distribution, centered on Eurasia, and are euryha ...

, caprellid, and caridean shrimps, as well as other

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

Reproduction and growth

''Hippocampus spinosissimus'' is an

species, with the female using an

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

to transfer eggs to an enclosed brood pouch on the male's stomach. The male then fertilizes and protects the developing

embryos 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 sper ...

before giving birth to tiny () independent young. Individuals reach sexual maturity when they are around .

Population

Although there have been no dedicated population estimates for ''H. spinosissimus'', analyses of seahorse trade and fisher surveys suggest population declines of at least 30% in the past 10 years. In specific areas these declines can be even more significant, with 80% population decline over two months occurring in the central Philippines due to targeted fishing.

Threats

The major threat to ''H. spinosissimus'' is overfishing. It is caught as bycatch in many artisanal and commercial fisheries throughout its range, such as in

Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

, the

and

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

. This species is one of the two most heavily reported species in trade - an indicator of the high levels of exploitation pressure from bycatch that is exerted on it.

Conservation

All ''Hippocampus'' species are listed under Appendix II of the

Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of intern ...

(CITES), which regulates the export of seahorses. Signed countries are meant to provide permits for seahorse exports, and ensure that these exports are not harmful to wild populations. This, however, becomes difficult when population information is unavailable and authorities cannot assess the

sustainability Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livi ...

of their seahorse exploitation. The challenge is increased further by the fact that most seahorses are caught as bycatch, so imposing export quotas has little effect on the impact to seahorses. Therefore, it is important that we gather information regarding the spatial and temporal distributions of seahorses, so that area restrictions can be imposed that are most effective in conserving populations.