Desert Ecology Chapter 6

Chapter 6 Animal Life Histories

Chapter Outline | Web Resources | Study Questions

Chapter Outline

Desert millipedes remain underground through much of the year. With rain, they venture to the surface where they feed on the bark of shrubs and plant debris. This millipede, in the Chihuahuan Desert, is 13 cm (5 inches) long.

Introduction
Timing Is Critical
    Environmental cues
    Use of temporary water by amphibians and aquatic animals
    Insect metamorphosis
Reproductive Adaptations
    Limiting water loss during reproduction
    Parthenogenesis
Social Insects
Migration

Web Resources

Scaphiopus couchii (Couch's Spadefoot Toad) outlines the natural history of this desert dweller. By Shauna Alexander of the University of Michigan.

A Pothole in the Road of Life provides interesting insights into life in desert potholes. By Leslie Mullen of NASA.

Pothole Ecology describes how a desert pothole comes to life. By Tim Graham of the USGS.

Desert Animals and Wildlife provides interesting facts, including life history descriptions, about common desert animals. From Desert USA.

Study Questions

1. In most temperate regions the life cycle of animals is primarily cued by seasonal changes in temperature and daylength. Not so in the desert. Describe the environmental cues desert animals use to time their activities. Include examples in your description.

2. As a group, amphibians are not ideally suited for desert survival. Nevertheless, a few amphibians, such as the spadefoot, do exist. a) List at least four characteristics of amphibians that make them poorly suited for desert life. b) Consider the spadefoot. Describe how it overcomes these seemingly unfit adaptations. (You may want to refer back to Chapter 5.)

Brazilian free-tailed bats emerge from Carlsbad Caverns each summer evening and after a night of feeding on insects, return at dawn. Each adult bat may consume up to 1/3 its own body mass in insects.

3. Remarkably some aquatic animals, such as fairy shrimp, are able to survive in the desert. Compare and contrast the survival strategies of fairy shrimp, an ephemeral plant (Chapter 2), and a nematode (Chapter 5).

4. Reproduction can greatly increase water loss but some desert animals have means to minimize this water loss. Describe the adaptations of small mammals that minimize water loss during reproductive activities.

5. Some desert species have foregone sexual reproduction. For example, several whiptail lizard species are entirely female. a) What are the advantages and disadvantages of asexual reproduction? b) Describe the niche of some parthenogenic whiptail species and how their niche may help them persist in the desert despite lacking the advantages of sexual reproduction.

6. Ants and termites are particularly common in the desert. Explain how their social way of life may benefit them in the desert.

7. Some animals, particularly birds, migrate to and from the desert. What proportion of desert birds are migratory, and where do they go?

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