Gray Whale Gray Whale Adaptations: The Head << Back to Main Lesson Click on drawing to see labeled enlargement The throat grooves are expanded on this Gray Whale. Photo Renee Bonner Baleen hangs from the whale's upper jaw and works to strain food out of gulps of water. Mostly Mouth for Eating Tons of Food When the whale is feeding, 3-5 throat grooves expand to hold vast amounts of sea water. In the Arctic feeding grounds each summer, an adult gray whale will probably gulp about a ton of food every day! The whale expands its throat to hold huge amounts of seawater and food, then compresses its throat and pushes the water out through the baleen plates in its mouth. The tongue can weigh 1000-3000 pounds (up to 1,300 kg). It represents at least 5 percent of the entire surface area of a gray whale's body. A special adaptation keeps the whale from having hypothermia (losing heat through its tongue) when its huge mouth is open to frigid Arctic seas for as many as 20 hours a day; its huge tongue has networks of arteries and veins that seem to act as heat exchangers that help conserve the whale?s body heat. Baleen takes the place of teeth for whales in the suborder Mysticeti. Baleen is made from a fingernail-like material called keratin. Baleen whales have a series of 130-180 fringed, overlapping baleen plates, 2 to 10 inches (5-25 cm) long, hanging like curtains from each side of the upper jaw where teeth might otherwise be found. Like giant combs or strainers, baleen plates filter water out and trap food inside the whale's mouth. The huge tongue is muscular and nimble to help the whale during feeding. In order to feed off the bottom of the ocean, the whale swims to the bottom, rolls on its side, and plunges its head a few inches into the muck. By expanding and contracting its throat grooves and retracting its huge tongue, the whale creates suction to suck mud and organisms into its mouth. The whale pushes the mud-food mixture around with its tongue, then pushes it out through the "curtain" of baleen. The food stays trapped inside. Then the whale uses its tongue to lick food off the baleen, much as you might suck peanut butter off the roof of your mouth, and swallows it. Gray whales also feed upon floating and swimming organisms, gulping in mouthfuls of nutrient-filled water and filtering the water through the baleen. Nostrils Move and Change to Blowholes What used to be nostrils in landlubbing whale ancestors slowly developed into one or two blowholes located at the top of a whale?s head. Whales inhale and exhale air through their blowholes. Because its blowholes are so high on its head, a gray whale can breathe by barely breaking the surface of the water. The skin around the blowholes has many specialized nerve endings that are sensitive to changes as the blowhole breaks the water?s surface. The whale can inhale and exhale in a fraction of a second. Muscles in a series of valves and plugs keep the blowholes closed when the whale is underwater. A swimming gray whale's mouth may be full of water, but it won't miss a breath because the blowholes connect directly to the lungs. Open blowhole on baby gray whales Adaptations for Sensing the World around Them Gray whales have just a small hole and no external ear on the head. Instead, a gray whale's jawbone plays a very important role in sound reception and hearing. The gray whale?s most important sense is hearing. The auditory nerve is relatively larger than in other mammals, and the parts of the brain responsible for hearing are highly developed.Unlike dolphins and killer whales, gray whales do not appear to use high-frequency sounds for echo-location. Because the eyes are located far back on the head, whales do not have good binocular vision like humans do. The gray whale must move its entire body to get a good look at something. It cannot even see something that's just in front of its nose. The eyes are small, about the size of a baseball. Although the eye and optic nerve are rather undeveloped in gray whales, grays seem to have fair eyesight in both water and air. A layer of cells at the back of the eye acts like a mirror to reflect light back to the retina over and over again. This is a great help in low light conditions, such as murky water. The retina also contains many rod cells, which are sensitive to low light. The white part of the whale?s eyeball is thick and resilient and can take high pressures without deforming on deep dives. Try This! Journaling Questions The food items they eat are incredibly tiny, but gray whales are very efficient feeders. Their metabolism is very low so they make efficient use of food energy, burning far fewer calories per day per pound of body weight than humans burn. How does this help gray whales in frigid water? How does it help them during their migration? How does it help mother gray whales when they have young babies? If this adaptation is so useful, why aren't humans adapted to be more efficient feeders?   Facebook Pinterest Twitter © 1997 – 2024 Journey North. All rights reserved.