The Pacific seahorse, Hippocampus ingens, is the largest seahorse species, reaching lengths up to 30 centimeters (about 12 inches). It inhabits the Eastern Pacific Ocean, ranging from Southern California and Baja California down to Peru, including the Galapagos Islands. This marine fish lives anchored to substrates in shallow, temperate, and tropical environments. Its large size and slow movement present a unique challenge when acquiring enough food to survive.
Daily Consumption Volume
The amount a Pacific seahorse eats is best measured in volume and frequency, as they consume a high volume of tiny crustaceans, not large “shrimp.” Due to their simple, stomach-less digestive system, food passes quickly, meaning they must feed almost continuously to meet metabolic demands. An adult seahorse consumes the equivalent of an estimated 5% to 10% of its total body weight daily.
This constant need for calories translates into thousands of individual prey items consumed daily. The animal is constantly hunting and striking at prey, potentially executing a feeding strike dozens of times per minute. This high-volume intake compensates for the small size of each individual meal.
Diverse Prey Items
The Pacific seahorse’s diet is specialized, consisting entirely of live, minute organisms that must be swallowed whole. Primary components are small, slow-moving crustaceans and zooplankton, often misidentified as “shrimp.” Specific prey items include copepods (small, free-swimming crustaceans) and amphipods (slightly larger, shrimp-like organisms).
Larval forms of other sea life, such as mysid shrimps and newly hatched brine shrimp, are also regularly targeted. The seahorse is an ambush predator, relying on its excellent camouflage to remain anchored and wait for a suitable organism to drift within striking distance. It targets these organisms because their small size allows them to fit entirely within the seahorse’s narrow, tube-like snout.
The Suction Feeding Mechanism
The Pacific seahorse is able to consume thousands of tiny prey items due to its specialized hunting technique known as pivot feeding, which uses vacuum suction. The seahorse remains motionless, often anchored by its prehensile tail, until a potential meal comes close to its snout. The strike is executed by a rapid, powerful rotation of the head, a movement called neurocranial dorsorotation, which brings the mouth close to the prey.
Simultaneously, the seahorse rapidly expands its buccal cavity, creating a strong, low-pressure vacuum that sucks the prey and surrounding water into its mouth. This suction mechanism is exceptionally fast and efficient, allowing the seahorse to capture evasive prey before it can react. Since the seahorse lacks a stomach, this feeding strike must be repeated constantly, as it cannot store and slowly digest food for later use.