SHORELINES : Fish Story : The bottlenose dolphin mysteriously came in with a warm water current in the 1980s--and stayed.

In the early 1980s, a warm water current known as El Nino traveled throughout the Pacific. On the tail of this current rode a playful, yet mysterious, creature that arrived in Ventura County and stayed.

We sometimes see this creature as it swims back and forth along the Ventura Coast, attracting an adoring following whenever it comes into sight. Some refer to it as Tursiops gilli, others call it Flipper and still others know it as the Pacific bottlenose dolphin.

Maybe it’s because the bottlenose dolphin has been around this area for such a short time that so much mystery surrounds it. Even experts are confounded and amused by this mammal. They will talk in technical, scientific terms and in the same breath use words like “magical” and “mythical.”

What they do know is that the bottlenose dolphin is one of about six species of dolphins in the area. From 30 to 50 of them hang out just off the shores of local beaches. Many travel as far north as Point Conception and some as far south as Ensenada.

Exactly why El Nino’s dramatic climate change brought them here is unclear, but research published by the Channel Islands National Marine Sanctuary suggests that the dolphins came north to follow their food--smelt, grunion and squid.

The warmth of El Nino was comfortable for the bottlenose dolphins, but conditions have changed.

So what’s keeping them here?

“I wish I knew the answer,” said Charles D. Woodhouse, curator of the vertebrate zoology department at the Museum of Natural History in Santa Barbara.

“They have a blubber layer, and they’re warm-blooded, so they probably can withstand cooler temperatures,” he said. “I think it’s so easy to think about temperature as a factor, but it’s so much more than that, especially in water. They dive down 30 feet, and they’re in a different temperature.”

Woodhouse said bottlenose dolphins might be hanging around because they like the food. “Before El Nino, these animals hadn’t learned about coming north. They are like a lot of marine animals,” he said. “If they accidentally find a new foraging environment, they’ll exploit it.”

So it looks like bottlenoses are here to stay, at least until another dramatic change in their environment. It’s probably a good idea, then, to get to know them better.

Sleeping habits: No one seems to know for sure how bottlenose dolphins sleep, but one thing is certain--they do it very lightly.

“In the wild, it’s thought that they sort of catnap,” said Gary Wilson, coordinator of the Exotic Animal and Training Program at Moorpark College. “Maybe they sleep a minute or two at a time.”

Woodhouse, on the other hand, cited research by a colleague in Santa Cruz. “They may sleep half a brain at a time,” he said. “One eye open.”

Being mammals, they need air, so the dolphins sleep at the water’s surface. Because of their layer of fat, they tend to be buoyant and because of their lung capacity, they can stock up on air.

Playfulness: “They’re naturally playful. I’ve seen them body surfing in the waves, which apparently doesn’t serve any function other than play,” said Wilson. “They seem to like to ride on the bows of boats too.”

On the other hand, when they jump and splash loudly in the wild, they may be doing more than just entertaining themselves.

“You have the impression that they’re just having a good time, and that may be the case, but another idea is that they are actually communicating with each other,” said Wilson. “It also may have something to do with driving fish they are feeding on toward other dolphins.”

Sonar: Dolphins produce a powerful sonar they use to communicate with one another and to help them “see” in murky water. Wilson said they use the sonar at night, close to shore, so they can feel their way around. He said they can seek out food with their sonar and there is even a theory--yes, another theory--that the sonar is used to stun the little fish they eat.

Woodhouse has his doubts about this ability to stun. “That’s the Big Bang theory,” he said. “The question is, is the dolphin stunning the fish or chasing the fish until it builds up such oxygen deprivation that it is worn out. It’s yet to be proven.”

Such theories and speculation seem to enhance the fondness people have for these dolphins. Whenever they make an appearance near shore, it’s a safe bet people will crowd around to look at them.

“I think there is something from them that people pick up. It’s they’re own energy,” said Donna Alija of the Delphys Foundation in Carpinteria, an organization working to educate people about dolphins and whales. “If you look at the stories that have been told, there’s always been a magical feeling between them and people.”

John Johnson, curator of anthropology at the Museum of Natural History, related this well-known legend: “The Chumash believed their population originated on the Channel Islands,” he said. “There was a rainbow bridge that crossed the channel from the islands to the mainland. People traveled that bridge, and whoever looked down fell in and became a dolphin.”

Of course, said Johnson, this “ancient” legend may have been invented relatively recently. There are various theories about that too.