LONG BEACH — The missile-like shape of the endangered blue whale has been spotted off Long Beach, meaning the largest mammal on Earth has started its migration along the West Coast, giving whale-watching enthusiasts plenty to see.

With adult whales reaching the size of about two buses, the Balaenoptera musculus — the scientific name of the animals — is larger than the largest dinosaur.

Marine mammal enthusiasts can now visit the Aquarium of the Pacific’s award-winning exhibit, “Whales: Voices in the Sea,” with a newly added interactive kiosk that educates guests on the environmental threats facing whales.

As part of the exhibit kickoff, visitors can see the largest mammal ever known to exist for themselves in a three-hour whale-watching excursion. Spectators will board a high-speed catamaran with stadium-type seating next to the aquarium and have a chance to see endangered blue whales. The tours can be bought with admission to the aquarium and are expected to continue until early September.

On one of these recent excursions, Missy Borodulin, a Mission Viejo resident and whale-watching enthusiast, gripped the boat’s rail and gasped as she watched one of the blue whales swim close by.

“You never realize how powerful nature is,” Borodulin said. “This makes you feel alive and makes you think about the bigger picture. I think, ‘Do I make this place inhabitable for these creatures?’ It makes you think more about them.”

Blue whales migrate each summer from the Mexican coast north as far as Alaska, though scientists don’t know the whales’ exact destination. They are estimated to number 10,000 to 25,000 worldwide, according to the World Wildlife Fund.

“I think what is great is that on every trip there is an educator on board to discuss the importance of animals,” Claire Atkinson, Aquarium of the Pacific communications manager, said of the tour. “The wild environment is very close to us, and it’s great when people get to experience this. It makes you think about what you do in your everyday life that affects these animals.”

Michele Sousa, senior marine mammal biologist at the Aquarium of the Pacific, noted that although they are called blue whales, they are gray in color. They are considered blue because of the blue sheen around them while underwater.

Barbara Long, vice president of special projects for the aquarium, said the exhibit talks about different species of whales, how they communicate in the ocean and their population.

“Right now, they are migrating and are here because they are feeding and there are large amounts of krill here. It’s their feeding spot,” Long said.

“To me, seeing them move through the water makes it special. We are an urbanized area and yet, many species of whales come here. I get to see one of the most magnificent species in the water in Long Beach’s backyard.”

Quietly looking out at the ocean, Roberta Brown and her young son, Ian, sat and relaxed inside the catamaran after watching a mother and baby blue whale swim up to the surface for air.

Ian said he thought it was cool getting a closer look at the mammals’ entire bodies and their sizes.

“This is something we have been wanting to do for ages,” Brown said. “I’ve been scared to do this because I’m prone to seasickness, but you have to take a risk and do something that you have to do when living in Southern California.”