The Lined Seahorse

During the summer months, the Maryland Coastal Bays Program has the pleasure of running weekly seining programs for both educational and scientific purposes. This past June, we caught one of my favorite creatures, a lined seahorse! Seahorses are not caught as consistently as many of the regulars we see while seining, so this was a rare and exciting catch. Also called Northern seahorses, this species dwells among patches of submerged aquatic vegetation (SAV) in the summer months and then moves out to deeper water in the winter. They are notoriously weak swimmers, so their survival depends on their excellent camouflaging ability to conceal from predators.

Reproduction

Lined seahorses are monogamous, meaning they partner with their mates for life. Females lay their eggs inside of the male’s brood pouch. The male then fertilizes the eggs and keeps them safe and warm against his body for the next two weeks until the young hatch. The juvenile seahorses are projected from the male’s pouch in a cloud of 100 to 300 of their siblings.

Diet

The lined seahorse’s palate favors small crustaceans like crabs and shrimp. They capture their prey by actively camouflaging to blend in with their environment and staying perfectly still by using their tail to anchor to a stationary object. When their preferred targets pass by, they use their long, tubular snouts to suck them in. Seahorses lack both teeth and a stomach, so food passes through them rapidly and their digestive systems are highly inefficient. This means they must eat almost constantly, some days as many as fifty times and up to 3,000 brine shrimp!

Threats and Conservation Efforts

The World Conservation Union categorizes lined seahorses as “vulnerable”, with their populations estimated to have decreased by at least 30% over the past 10 years. Unfortunately, several factors threaten these fish, including habitat degradation and loss, being caught as bycatch in fishing trawls, and their exploitation for aquariums, traditional medicines, and collector’s items. Efforts have been taken all over the world to restore the ever-declining populations of seahorses. Some U.S. states, such as New York, have passed legislation prohibiting the harvesting of seahorses as collector’s items (collection is still permitted for scientific and educational purposes). Also, many organizations have taken strides to protect and restore SAV, such as eelgrass, where lined seahorses reside.

Fun Fact: The eyes of a Lined seahorse can move independently of each other!

About the Author: 

Christy Ferguson is a summer intern with the Maryland Coastal Bays Program and recent graduate from the University of Maryland Baltimore County with a BS in environmental science and geography. This summer she will be assisting with water quality monitoring, restoration monitoring, wetland assessments, seining at Castaways, and Ocean City Estuary Explorers camp. Christy loves getting to see new wildlife species out in the wild and learning to identify them.