Skulls


Have you ever found a skull in the woods or weeds? Were you able to identify which animal it belonged to?

Here are a few skulls for you to study. Some of these skulls belong to predators, animals that hunt and kill to eat. Predator skulls have eye sockets that allow them to look forward toward their prey. What other observations can you make about these skulls that help them as predators? Which of these animals eat only plants? What about their teeth make eating plants easier? Most plant-eaters are prey animals. What adaptations do they have to protect themselves from hungry predators?

Match the description of the animal (1-6) with its picture (A-F) and its skull (I-VI). You will end up with an answer such as 1, F, IV. When you’re done, check your answers.

  1. This mammal is found throughout western Texas and the Brush Country of South Texas. It has daggerlike tusks and crushing molars that enable it to eat various types of cactus (especially prickly pear), mesquite beans, and other vegetation. As many as thirty of these animals may roam together in one herd. Although it usually avoids man, it has been known to slash hunters or hunting dogs with its long, sharp tusks. It makes a loud popping sound with its teeth as a warning signal and squeals if startled. Adults weigh between thirty and fifty pounds.
  2. This nocturnal mammal spends the daylight hours sleeping in its den in a hollow tree or log. It is quite fond of water and does most of its feeding in or by the water’s edge. Although classed as a carnivore, this animal is not a specialized feeder. It eats fruits, nuts and corn as well as fish, birds, snakes, insects and crayfish. As a result, it has flat-crowned molar teeth that are adapted for crushing instead of the shearing or cutting molars of the dog and cat families. Adults weigh from ten to thirty pounds.
  3. This imported mammal is a member of the rodent family and has large gnawing incisors characteristic of this group. It prefers a semiaquatic habitat and can be found in swamps and marshes or along the shores of lakes and rivers. It is equally at home in either fresh or salt water. Aquatic and semiaquatic vegetation is its staple food, but a nearby garden with cabbage, carrots, and sweet potatoes also may be raided by this South American native. Adults normally weigh eighteen to twenty-five pounds.
  4. This mammal is a very active digger and will have several unoccupied dens or burrows that are used for escape shelters. Although most of its body is covered with a shell-like armor to help protect it from predators, its sparse hair makes it susceptible to cold weather. In fact, long periods of freezing weather can kill a whole population. Its long snout, well suited for probing the ground for insects, is equipped with twenty-eight to thirty-two peglike teeth. Adult males weigh twelve to seventeen pounds and females eight to thirteen pounds.
  5. This predatory bird has a huge appetite. It can swallow whole rats, mice, and small birds. Larger animals are torn into pieces by its sharp, hooklike beak. Bones, feathers, and fur are all eaten. The parts that cannot be digested are compressed into a pellet about one inch in diameter and two inches long. The bird then regurgitates the pellet. This bird is well adapted to night hunting, and its flight is almost noiseless. It has extremely large eyes that can take advantage of the dim light of night.
  6. This large, long-necked wading bird often is mistaken for a crane. It uses its spearlike bill to catch food and defend itself against enemies. In addition to fish, this four-foot bird with its six-foot wingspan eats snakes, mice, frogs, eels, salamanders, insects, and an occasional marsh bird. When in flight, it folds its long neck and rests its head on its shoulders. Marshes, swamps, rice fields, rivers, and shorelines are choice habitat.
  7. This medium-sized wading bird prefers the shallow water of marshy areas, wet fields, and tidal flats for feeding areas. Crayfish, fiddler crabs, snakes, and insects fall victims to its long, curved bill. When in flight, this bird keeps its neck outstreatched and alternates between flapping and gliding.
Bird with huge eyes and sharp beak; Courtesy Terry Spivey, USDA Forest Service

A

Skull with deep eyes and short nose

I


Mammal with large gnawing incisors; Courtesy David Arbour, USDA Forest Service

B

Small skull with long, curved beak

II


Animal with long, flattened head

C

Skull with large eye sockets and short, sharp beak

III


Bird with long, curved beak; Courtesy Kenneth M. Gale, www.forestryimages.org

D

Skull with wide-set eyes, long nose and long sharp incisors

IV


Bird with narrow head and spear-like bill

E

Skull with short head and large gnawing incisors

V


Mammal with long sharp tusks

F

Skull with long snout and flattened shape

VI


Mammal with flat-crowned molar teeth; Courtesy Ricky Layson, Forest Resource Consultants, Inc., www.forestryimages.org

G

Skull of bird with spearlike bill

VII


Answers


Additional Information:

Ilo Hiller
1983 Skulls. Young Naturalist. The Louise Lindsey Merrick Texas Environment Series, No. 6, pp. 36-37. Texas A&M University Press, College Station.

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