Description & Behavior

Pacific seahorses, Hippocampus ingen (Girard, 1858), are one of the largest of the 34 known species of seahorses in the world, and can reach up to 30 cm in length. The Genus name is derived from the Greek hippos or “horse” and campus or “sea monster.”

Hippocampus ingens

Dorsal spines (total): 0-0; Dorsal soft rays (total): 18-21. Description: (based on 19 specimens): Adult height: 13-19 cm. Rings: 11+39 (38-40) Snout length: 2.3-2.4; head length: 2.1-2.5cm. Dorsal fin rays: 18-21 covering 2+1 rings. Pectoral fin rays: 15-17. Coronet: medium-high, tilted backwards with 5 well-defined points, sharp edges or flanges at top. Spines: variable, from low rounded bumps to well-developed blunt-tipped spines. Other distinctive characters: prominent, long (drooping), rounded, single cheek spines; prominent eye spine (may be broad or almost double); males commonly have a prominent keel; sexually mature females often have a dark patch below the anal fin. Pacific seahorses are reddish-maroon, gray, yellow and gold; various shades of brown; and may have fine white light and dark markings running vertically down their bodies.

World Range & Habitat

Pacific seahorses are found in the Pacific Ocean from San Diego in California to Peru including the Galapagos Islands. Pacific seahorses are nocturnal and are found in offshore waters, usually at 10 m or deeper. They are occasionally caught at the surface. They are often camouflaged within the branches of gorgonians and black coral trees where they are seen to curl their tail around the branches. Have been found in the stomachs of Pacific yellowfin tuna and bluefin tuna.

Feeding Behavior (Ecology)

Seahorses feed on bottom-swarming organisms such as mysids and other plankton.

Mysids are very small (seldom exceeding 30 mm in length) shrimp-like crustaceans which can be found throughout the oceanic water column and are also found in freshwater environments as well. Some mysids feed on small particles which they collect by grooming their body surface, whereas others are predators of zooplankton. Some mysids are scavengers. Marine mysids often are found in large swarms and are an important part of many fish diets. Mysids are also called “opposum shrimp”, because of the brood pouch present in all mature females.

Mysids at present include more than 1,000 species, widespread over all the continents, inhabiting coastal and open sea waters, as well as continental fresh waters, several taxa occurring also in different groundwater habitats and in anchialine caves.

Seahorses lack teeth and stomachs. Prey is consumed by sucking it through their bony snout with a rapid snap of the head.

Life History

In seahorses, the female uses her ovipositor to deposit her eggs in the male’s brood pouch where they are fertilized and remain until hatched. After a period of time, varying from ten days to six weeks, depending on the species and water temperature, the male gives birth to hundreds of live, tiny, seahorses, which are miniature replicas of the adults. Mode: dioecism, fertilization: in brood pouch or similar structure, and gestation period is 14-15 days depending on temperature.

Conservation Status & Comments

Seahorses are in constant risk from overfishing and habitat destruction. Seahorses are exploited for traditional medicines and as aquarium fishes, and their habitats are among the most threatened marine environments. According to Project Seahorse of McGill University in Montreal, in the last five years many seahorse populations have declined by 50 percent.

Pacific seahorses, Hippocampus ingens, are listed as Vulnerable (VU A4cd) on the IUCN Red List of Threatened Species:

A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable (see Section V), and it is therefore considered to be facing a high risk of extinction in the wild.

References & Further Research

Biology of Pipefishes, Pipehorses & Seadragons – Project Seahorse
David Hall’s Encounters in the Sea
Wilhelm Bögershausen – clownfish underwater picture gallery

Research Hippocampus ingens @
Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS

Search for Pacific Seahorses @
Flickr ~ Google ~ Picsearch ~ Wikipedia ~ YouTube