Four giant Pacific seahorses, one of the ocean's most elusive creatures, are now on display at the Roundhouse Aquarium at the end of the Manhattan Beach Pier.

The juvenile seahorses (Hippocampus ingens) are classified as Vulnerable on the IUCN Red List of Threatened Species and listed on CITES Appendix II, which restricts international trade. They are the only seahorse species found in the eastern Pacific Ocean, reaching up to 12 inches tall, among the largest in the world.

What makes them so hard to spot in the wild is the same thing that makes them fascinating behind glass: giant Pacific seahorses are ambush predators. They camouflage themselves in kelp, eelgrass and soft corals, shifting color to match their surroundings, then wait motionless for small crustaceans to drift past before sucking prey in whole.

They have no teeth and no stomach.

The species faces mounting pressure globally. Conservation researchers estimate more than 20 million seahorses are sold each year for use in traditional Chinese medicine, the aquarium trade or as dried curios. Hippocampus ingens accounts for the majority of species identified in medicinal markets worldwide because of its large size and smooth texture.

Another detail that sets these creatures apart: the males carry and birth the young. Females deposit eggs into the male's brood pouch, where they develop over a 14-day gestation period. A single male can brood up to 2,000 eggs at once.

The arrival of the four seahorses was first reported by Easy Reader News on Thursday, July 30, and confirmed by NBC Los Angeles on Tuesday, Aug. 4.

The Roundhouse Aquarium, led by executive director Grace Adams and operated by the nonprofit Oceanographic Teaching Stations (OTS), is free and open to the public. The aquarium welcomed more than 220,000 visitors in 2024 and provided hands-on marine science education to more than 22,000 students, including over 10,000 from low-income communities, according to its annual report.

Summer extended hours run through Sept. 13: Fridays, Saturdays and Sundays from 9:30 a.m. to 7:30 p.m. Regular hours are Monday through Friday, 2–7 p.m., and Saturday through Sunday, 10 a.m.–7 p.m.