More than twenty-five years earlier a fisherman told one of the first dolphin researchers at Shark Bay about a dolphin that had a horrible growth on his face. But when the biologist found the dolphin, she realized the "growth" was actually a sponge.
She soon spotted other sponge-carrying dolphins, mostly females with calves. All frequented the deeper channels that gouged Shark Bay's sandy flats. It wasn't obvious why the dolphins carried sponges, since they didn't seem to be eating them.
Maybe the dolphins just liked to give the ocean floor a good scrub now and then. Maybe there were squeegee-carrying dolphins as well. And dolphins looking for a place to plug in a vacuum cleaner.
Okay. Maybe not.
What that dolphin scientist had observer was a novel example of a dolphin making and using a
tool.
Dolphins have tender noses (rostrums), and these females had learned to protect their tender rostrums while they rooted along the rough coral- and rock-strewn channel bottom, hunting for a particularly slow and apparently not-too-bright prey called the barred sand perch. Eventually fifty-five dolphins, all related to the first sponger, were seen using the same tool, one they broke off from the sponges growing along the channel between the warm, shallow bay and the deeper, colder ocean. With this handy gizmo, Dodger, Puck, and their extended family had discovered how to shape and use a tool in the way only humans, a few primates, and a few birds had been observed to do, an example of a high-level intelligence at work. These animals had also developed a
culture, a pattern of learned behavior observed to be passed down through three generations among the dolphins of Shark Bay.
That dolphins can come up with innovative tools and pass down learned behavior to their calves is more proof that dolphins are the Einsteins of the sea, and in
The Dolphins of Shark Bay (Scientists in the Field Series)
(Houghton Mifflin Harcourt, 2013), author Pamela S. Turner follows marine biologist Janet Mann observing the dolphins of Shark Bay on the coast of western Australia as she compiles data on other dolphins with their own inventive forms of hunting:
We're looking for Reggae and the Beachers. That might sound like the name of a steel drum band, but it's actually a group of female dolphins with a crazy talent.
Reggae's searching for small schools of fat mullet. The beach--a steep, sandy slope--is ideal for her hunting strategy.
Reggae herds her victims closer and closer to the beach.
Then without a warning, she makes her kamikaze run. Panicked mullet dart toward the beach; Reggae rockets after them, her momentum carrying her completely out of the water. There's no escape for the mullet.
Beach hunting is a dangerous method that requires a long apprenticeship. Spongers are rare; beach hunters such as Reggae are even rarer.
Shark Bay's dolphins display other unique forms of hunting with tools, such as shell-shaking--chasing small fish into a large, empty shell, and holding them above water until the dazed fish can be shaken out and snapped up. One female, Square, forages only at night, for nocturnal squid, a feeding style rarely observed in cetaceans; one named Wedges has perfected a high-speed torpedo attack on enormous fish; another has learned to echolocate sea birds floating on the surface with their prey and slam into them to grab the catch-of-the-day.
Why are these female dolphins so inventive? Janet's theory is an inversion of the old saw, "Necessity is the mother of invention:"
Among dolphins, invention is sometimes a necessity of motherhood. Clever moms eat better. Their calves survive more often.
Like others in Houghton-Mifflin's much-lauded
Scientists in the Field
series, Turner's
The Dolphins of Shark Bay (Scientists in the Field Series) combines skillful pacing and abundant humor in her text and outstanding nature photography by Scott Tuason to raise some of the big questions in animal science: how can intelligence be observed; do animals have a "culture" like humans; and what qualities in the environment contribute to learned intelligent behavior?
Upper elementary and middle school students will find this book both entertaining and mentally stimulating, with a cast of varied dolphin characters, from "perfect mom" Puck, with many adoring daughters and grandchildren, to "welfare queen" Nicky the moocher, with only one hardscrabble surviving offspring, who lives by begging fish from tourists and fishermen. Alternatively, there are the roving gangs of male dolphins, playfully named the Red Cliff Rascals, the Prima Donnas (whose T shirts should read "
Herding Shark Bay Females Since 1990"), The Blues Brothers, and The Punks, who form herding trios to help their leader win a fair maiden dolphin. Then there are the playful kids, like Cheeky, Samu, and India, who actually take turns being "It," in a pretend game of herding through the waters of their playground in Shark Bay. Dolphins are fascinating mammals, and young readers who love them will heartily enjoy following these personable scientists in the field with the dream job of dolphin-watching every day.
Labels: Animal Intelligence (Grades 3-9), Dolphins--Habits and Behavior, Marine Animals
series is a part of the five levels of Blastoff Readers which highlights popular marine animals with texts with Accelerated Reader levels ranging from 1.7 to 2.2. Sentence structure is simple and vocabulary is controlled, with new topical words presented in boldface, and also listed in the book's glossary. Illustrated with glowing closeup photos of a wide range of appealing sea animals, kids are sure to be drawn to the subject of each book.
which describes the different coloration of juvenile and mature parrotfish and provides up close and personal views of those famous coral-nipping teeth. The simple text also describes the amazing process by which parrotfish convert the coral which they ingest in the process of harvesting algae for food into the sparkling white sand which covers some of the the world's favorite beaches.
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