Both the American horned lizards (Phyrnosoma, Phrynosomatidae) and the Australian thorny devil (Moloch horridus, Agamidae) eat ants almost exclusively
Suggest an explanation for the convergence of ant-eating specialists in these two families on a short-legged, stocky body form and a spine-covered body.
Ants have a large amount of keratinized exoskeleton in relation to their internal contents. The lizards cannot digest the exoskeleton, so they must eat large numbers of ants to obtain the energy they need; the stocky body form is probably needed to accommodate a large stomach and intestine. These lizards capture ants on the substrate and do not have to chase them, so long legs would probably be more hindrance than help. A stocky, short-legged lizard cannot run to escape predators, and the spines provide a measure of defense. (E. R. Pianka and H. D. Pianka. 1970 . The Ecology of Moloch horridus (Lacertilia: Agamidae) in Western Australia. Copeia 1970:90-103; and E. R. Pianka and W. S. Parker. 1975 . Ecology of horned lizards: A review with special reference to Phrynosoma platyrhinos. Copeia 1975:141-162)
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Answer the following statement true (T) or false (F)
Generally the hormones secretin and cholecystokinin which are released by duodenal enteroendocrine cells will ________
A) speed the churning of the stomach B) increases the output of stomach acid C) speed the activity of the jejunum D) slow the activities of the stomach
What does the depolarization of the transverse tubules (T-tubules) promote?
A) binding of acetylcholine to ligand-gated sodium ion channels B) release of calcium from the sarcoplasmic reticulum C) entry of sodium ions into the muscle fiber through voltage-gated sodium ion channels D) release of acetylcholine from vesicles in the motor neuron into the synaptic cleft
Which sympathetic pathway involves a preganglionic neuron that synapses with a ganglionic neuron in a sympathetic trunk ganglion, but the postganglionic axon does not leave the trunk via a gray ramus?
A. Spinal nerve pathway B. Postganglionic sympathetic nerve pathway C. Adrenal medulla pathway D. Splanchnic nerve pathway E. None of the choices is correct.