The hedgehog seahorse (''Hippocampus spinosissimus'') is a species of fish of the family Syngnathidae. It inhabits coastal waters from India and

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

to Taiwan and northern

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is threatened by

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 ...

, as both targeted catch and

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

. This species is ovoviviparous, 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. 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 Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through ...

and corals 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 systems, occupying sand or silt bottoms, to a maximum depth of . In the central Philippines, 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 fans ...

, sea stars,

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 ...

, 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 or hard corals. 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 such as

copepods Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

, amphipods, and gammarid, 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.

Reproduction and growth

''Hippocampus spinosissimus'' is an ovoviviparous 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

. It is caught as

in many artisanal and commercial fisheries throughout its range, such as in Cambodia, Malaysia, Thailand, the Philippines and Vietnam. This species is one of the two most heavily reported species in trade - an indicator of the high levels of exploitation pressure from

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), 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

, 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.