Yellow Seahorse

In the exhibition: the yellow sea horse can be viewed in the Biodiversity Zone, after the Tropical Lagoon.

Geographic distribution: across the entire Indo-Pacific region (Japan, Philippines, Indonesia, Australia, Polynesia) and in the Red Sea.  

Habitat: underwater algae and seagrass beds in shallow waters, from 0 to 8 m.

Description:  its multicoloured appearance makes the seahorse look like an ”anomaly” of nature - it has the head and neck of a horse, an exoskeleton or ‘armour-plating’ like an insect, a prehensile tail like a monkey, the rotating eyes of a chameleon and the male has a kangaroo-like marsupial pouch, called a marsupium. Its posture is also remarkable because its head is tilted at a right angle to its body. Instead of scales, as in other fish, seahorse bodies are covered with a layer of skin stretched over a series of bony plates. While it is a fish, it has no pelvic fins and instead of a caudal fin it has a tail. The seahorse’s lack of fins makes it a very poor swimmer. While it can move using its tail, it often just drifts with the currents. Lastly, the seahorse has no teeth, but doesn’t need any because its food is microscopic.

Biology: sea horse reproduction is based on ”paternal brooding”, meaning that it is the male which gives birth to the offspring. After a complex mating ritual, the female lays her eggs in a pouch located on the stomach of the male; the male then fertilizes them and the pouch closes until the eggs hatch. The pouch has exactly the same role as the uterus in mammals. When the gestation period is over (about 1 month) the baby seahorses are ejected from the pouch by the father’s abdominal contractions.

Diet: sea horses feed on small crustaceans and other microorganisms which abound around seaweed.

Size: ranges from 5 mm at birth to a maximum of 18 cm as an adult in the natural environment. In captivity (in aquariums) Hippocampus kuda are generally smaller, at around 15 cm. Certain sources claim some can reach 20 to 30 cm.

Threats and protective measures: the yellow sea horse is listed as vulnerable by the IUCN global red list. Sea horses are too often caught in trawler nets and fall victim to overfishing and trade (including trafficking) for amateur aquarium enthusiasts, as well as for the Asian market (principally Chinese) where they are used in traditional medicine. On top of this the destruction of their habitats is degrading their living conditions.

Species characteristics and ability to occupy an ecosystem niche in the context of biodiversity: sea horses are adepts at mimickry. They blend into the marinescape by adopting the dominant colours of their immediate surroundings and can even display coloured spots or bands on their bodies. To be invisible to their predators, which include frogfish, rays and sharks, they remain motionless, which also makes them very difficult to spot in their natural environment.They also hunt for food by remaining motionless. Like the chameleon, their eyes are independent and their visual acuity enables them to follow their prey for a distance of up to 4 cm. At the right moment, they stretches out their ‘protractile’ mouth (snout), create a strong suction and suck up their victims along with the water around them. 

Resilience: both their origins and their evolution remain a mystery. They have stimulated man’s curiosity for a long time. The name sea horse comes from Pliny the Elder in 79 AD, but the very first reference dates back to the philosopher and scientist Aristotle, who wrote about the animal that it “tears itself apart during the mating season”. The sea horse combines the features of many other species, which is what makes it such an extraordinary species and also what has made it such a well-established figure in myth and legend.

Services provided to humanity: the dried powder of the sea horse is mixed with fat and vinegar and is thought to prevent baldness. Brewed in wine, its powder is said to make a virulent poison. A large number of recipes, potions and various balms have been made because of the magical powers that have been attributed to it.Today, these fish are very popular in Chinese traditional medicine. The sea horse is especially popular as a cure for: incontinence, senility, blood circulation, asthma, skin ailments,  arteriosclerosis, impotence, angina, heart disease, migrain and post-natal depression, etc. They are usually brewed by boiling for 2 to 3 hours before being consumed.They are nevertheless inedible.