A rare Pacific seahorse was recently spotted off California's Long Beach coast. Experts say the marine creature likely wound up in the Alamitos Bay due to unusually warm waters brought by this year's El Niño event.

Diver Roger Hanson caught this unexpected swimmer on video nonchalantly gliding in about four feet of water, according to CBS News. Pacific seahorses inhabit coral reefs as far south as Peru and hardly ever found north of San Diego. But this is second time within the last month that Hanson has spotted one of these spiny curvaceous creatures in California waters.

"I was shocked because I know that that's a once in a lifetime moment," said Hanson, who has completed more than 5,000 dives, including 1,200 excursions in water below Alamitos Bay.

Will rare marine creature sightings become the new norm?

"It's rare, I would say, in normal years," Sandy Trautwein, curator of fish and invertebrates at the Aquarium of the Pacific, said in a statement. "But I would say in the past year, because of the warm water influx we've had, it isn't that rare."

In fact, these seahorses are not the only unusual species making their way north: in San Diego, there are jellyfish blooms and several sightings of venomous yellow-belied sea snakes. Thousands of tiny red crabs also washed up on beaches in Orange and San Diego counties last June.

In addition to the El Niño conditions, "The Blob" -- an unusually warm mass of ocean water found in the Pacific -- could help explain why so marine creatures are being found outside their natural range.

Pacific seahorses listed as a vulnerable on the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species, as populations are thought to be declining due to overfishing and the ornamental wildlife trade.

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