Tiger tail seahorse  (Hippocampus comes)

The tiger tail seahorse is classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Named for its black and yellow striped tail, the tiger tail seahorse (Hippocampus comes) is an unusual-looking fish, with an upright posture, curved trunk, and grasping, prehensile tail. The head, which is positioned at right angles to the body, bears a long, tubular snout, and the eyes are able to swivel independently. Unusually for a fish, seahorses lack scales, and the skin is stretched over a serious of bony plates which appear as obvious rings around the trunk and tail. The dorsal fin is used for locomotion, and two small, ear-like pectoral fins are used for steering and stability (2) (4) (5) (6). Unlike most other seahorses, very young tiger tail seahorses possess a reduced caudal fin, which is lost in adults (6).

Seahorses are masters of camouflage, and are able to change colour or possibly even grow skin filaments over time to better blend in with the surroundings. Rapid, short-term colour changes can also occur during courtship or other social interactions (2) (4) (6). The tiger tail seahorse can vary in colour from yellow to black or brown, often with mottled patterns on the body, and with fine white lines radiating from the eyes. The striping on the tail may not be visible in all individuals, and body colour may change as the seahorse matures (2) (7) (8) (9). The top of the head bears five distinct knobs or spines, often with a dark band near the tip, and there are double spines on the cheeks (2).

The tiger tail seahorse is found in the eastern Indian Ocean and western central Pacific Ocean, and has been recorded from the Philippines, Indonesia, Malaysia, Singapore, Vietnam, Thailand and India (Andaman Islands) (1) (2) (7).

The tiger tail seahorse inhabits coral reefs, sponge gardens, seagrass beds and floating Sargassum seaweed, at depths of up to 20 metres (1) (2) (7) (9) (10). Whilst adults are usually found in reef habitats, typically grasping onto coral, sponges or seagrass, juveniles usually occur in Sargassum beds, which may provide better protection from predators and strong currents (2) (7) (8) (9).

Intriguingly, it is the male rather than the female seahorse that becomes ‘pregnant’, the female depositing the eggs into a specialised brood pouch at the base of the male’s tail, where they are fertilised and then protected and nourished for the duration of development (2) (4) (5) (6). After two to three weeks (2), the male undergoes several hours of labour, actively expelling the young from the pouch (4) (5) (6). The newborn tiger tail seahorses measure around ten millimetres in length (11), and are independent at birth, entering the water column as plankton and receiving no further parental care (2) (4) (6). The tiger tail seahorse is thought to breed year-round, and the male may undergo repeated pregnancies throughout the year, producing up to around 350 young at a time (2) (6).

The tiger tail seahorse forms monogamous breeding pairs, with the pair bond reinforced through daily greetings and through ‘promenading’ courtship displays (2) (4) (7) (10). This species may breed from six months to a year old, and is thought to live for around two to five years (1) (6) (7). Like all seahorses, it is an opportunistic predator, ambushing passing prey and taking anything small enough to fit into the mouth, including small crustaceans, invertebrates and even fish fry. Seahorses lack teeth, and prey is ingested by sucking it into the long snout (4) (6) (7). The tiger tail seahorse is most active at night, although this may be a response to fishing pressure (10), and pairs maintain a small home range (2) (10).

The tiger tail seahorse faces a number of threats, including capture for use in traditional Chinese medicine, as a curio, or for the live aquarium trade, and as incidental bycatch in other fisheries. It is also, like many seahorses, under serious threat from habitat degradation, due, for example, to destructive fishing methods, water pollution and siltation, and the farming of wild Sargassum beds, which are used to make kelp powder for export (1) (2) (7) (9). The shallow, inshore habitats typically used by seahorses are often highly affected by human activities, and the unique life history and social behaviour of these species makes them particularly vulnerable to any threats. For example, removal of one partner may stop the other reproducing, and adults may not disperse far to re-colonise depleted areas (1) (2) (4) (6) (10).

Although its year-round breeding and nocturnal activity may make the tiger tail seahorse less vulnerable to overfishing than some other species (10), it is reported to be one of the most commonly traded seahorses (1), and serious declines have been reported in some areas (1) (2) (6) (8) (10). The potential impact of global warming on the tiger tail seahorse is currently unknown (7).

In 2004, all seahorse species were added to the Convention on International Trade in Endangered Species (CITES), which should go some way towards regulating international trade in these species (3). The tiger tail seahorse has been studied in the wild in the central Philippines since 1995, as part of a conservation programme in the area (1), and has also been reported to occur in at least one marine protected area (MPA) there (10). Efforts are underway in some countries to develop sustainable farming of seahorses, to reduce the pressure on wild populations (5), and the tiger tail seahorse has been suggested as a good candidate for this (11). However, such initiatives may bring their own issues (12).

Further conservation actions recommended for the tiger tail seahorse include habitat protection and restoration, the promotion of sustainable use initiatives and market certification for the seahorse trade, assessments of the wild population, and an assessment of the impacts of both targeted and incidental catch. Further research into the ecology and life history of this fascinating species will also be important, in order to better inform conservation efforts (2) (6) (7).

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the conservation of this and other seahorses see:

• Project Seahorse:
  http://seahorse.fisheries.ubc.ca/
• The Seahorse Trust:
  http://theseahorsetrust.co.uk/