Casper the all-white dolphin pays a visit to Monterey Bay—just in time for Halloween.

Casper, the snow-white Risso's dolphin who has been a regional sensation since he first discovered munching on squid in the Monterey Bay in 2015, paid a visit to our shores this weekend.

“He was a youngster then,” says Nancy Black, a marine biologist at Monterey Bay Whale Watch, who has been observing this white dolphin since 2015. Despite his unusual appearance, Casper seems to be completely accepted by his herd and has been living closely with another dolphin believed to be his mother (a normal behavior among the species). 

“We saw him on Sunday again,” Black said on Tuesday, Nov. 2. “And just before Halloween. He has been hanging around.” And if he hangs around, he hangs with his family and associates—typically several hundred, if not thousands, of other dolphins. The dolphins come here to eat Monterey Bay squid.

Black says we don’t always know when Casper is around because Risso’s dolphins actually prefer deeper offshore waters where they can dive at least 1,000 feet to feed on squid of various kinds, most of them unknown to humans. “We don’t know much about species that live in deep seas,” Black says. “Sometimes we learn from what we can find in a dolphin’s stomach.” 

Casper stands out because he is the only all-white dolphin among his group. Local whale watchers gave him the name Casper—after the Friendly Ghost—not only because he is white, but also because trying to spot him is like ghost-hunting: a fascinating, time-consuming and often disappointing exercise.

Casper is one of a handful white Risso’s dolphins that has been spotted around the world and has been featured in the media all over the world. On average a  Risso’s dolphin can reach up to 13 feet in length, 1,100 pounds and live up to 35 years.