Ninth-graders Marvin Pascua, Delmar Esteban, Kieran Brughelli, Jordan Ragasa and Julian Lamphear, and eighth-grader Corey Chang had never seen a live stingray before yesterday, not to mention their biology instructor teaching a class from inside a reef tank at Sea Life Park.

The six boys were among 23 Damien Memorial School honors students who went to Sea Life Park for an intimate look at animal adaptations as part of a unit lesson on evolution and natural selection taught by Jill Sarchet.

Sarchet, 27, happens to be a certified diver who used to lead the "stingray ballet" for tourists at the park.

"I wanted them to see up close that animals are what they are for a reason, that everything serves a purpose," Sarchet said.

The shapes, colors and even mouths of different sea creatures are adapted to their lifestyles and survival. The bony plates in a stingray's mouth, for example, allow it to open shells and feed on clams.

Sarchet introduced her students to the seven stingrays in the tank — Ihu, Kupuna, Hoku, Kapili, 'Ele'u, Uku and Toshi — feeding them close to the viewing window. Ihu and Kupuna are spotted-eagle rays, while the other five are Hawaiian brown rays.

"It's interesting how they can train the rays to go from bottom feeders to being able to be hand fed in midair," said Lamphear, 15. "It shows they are somewhat intelligent. If they can learn this, they must be able to adapt to other conflicts, like environmental changes."

Ragasa, 14, was curious to know how Erik Swenson, head aquarist for Sea Life Park's reef-life department who narrated Sarchet's actions in the tank for the students, could tell the rays apart.

Observing they did behave differently, Ragasa noted it was like the rays had a pecking order on who got fed first. "It was like some would rest at the bottom rather than go after food in midair just to keep order," he said. "It's like real life."

Swenson explained that the rays have different characteristics that allow staff to identify them. The female rays — Ihu, Hoku, Kapili and Eleu — are more aggressive and prefer to be fed off the bottom. Kupuna is drawn to the diver's air bubbles, but has developed a disturbing trait of snapping at the top of a diver's head.

"Kupuna feels if he keeps bugging us he'll get fed and it seems he gets his reward," Swenson said.

'Ele'u is identifiable by bumps above her eyes, Toshi by his unusually long tail for a male and Kapili because she's "just crazy," Swenson added.

Swenson noted that Toshi and Uku hang at the bottom at feeding time, not to avoid the hassle, but because they know the divers will eventually come to them with food.

The students agreed that the outing, especially with their own teacher in the tank, was a unique learning experience.

"It was neat to see things in action," Lamphear said.

Ninth-grader Christyen Flores, 14, added, "On the TV screen, you only see what's on the screen, not everything else around it like we saw. I liked it."

Of his teacher's efforts, Flores said, "And she communicated with us without saying anything."

Reach Rod Ohira at rohira@honoluluadvertiser.com.