The food web in the hot desert biome is a simple
one. Life in this hot, dry environment is challenging, requiring adaptations from
both animals and plants. The soil is often dry, and desert winds carry fine dust
particles away, leaving a stony landscape. Plants that live in the desert year round
have evolved special adaptations for capturing and storing water. Adaptations include
secreting a waxy substance to protect their leaves from drying out, thorns and spines
to keep hungry animals at bay, and body shapes that can expand rapidly when water
becomes available. Plants have large networks of roots that lie near the surface
and can capture rain when it falls. One bush, the creosote bush, actually secretes
a substance in its roots that keep other roots out of its feeding area.
Many desert plants no longer have
leaves, or grow only very small ones. They have chlorphyll in their stems.
Many cacti do not have leaves at all. Their rounded bodies have a low surface to volume ratio, and the spines that protect them also cast a little precious shade
on their green bodies. Annual desert plants germinate, grow, and flower
quickly when there is a rainy year. They make small, hard seeds that may not sprout
for ten years or longer. Some perennial plants store moisture in underground tubers
Desert plants are the primary
producers. Animals that live in the desert feed on the plants' seeds,
flowers, and juicy bodies and leaves.
The plant-eating animals are the
primary consumers. These animals are small, and can get by on very
little food. Some desert dwellers are insects, and some, such as snakes and lizards,
are reptiles. Reptiles are "cold blooded" and they can survive on
only a little food. The warmth of the desert sun heats their bodies so that they
can move quickly. A few small warm-blooded animals, such as kangaroo also live
here. They hide from the heat in burrows, and come out at night to feed.
The secondary consumers
eat the plant eaters. Lizards eat insects: snakes eat lizards, insects, and little
desert rodents such as deer mice and kangaroo rats. Scorpions and tarrantulas
also eat insects. They have exoskeletons, which help them to conserve moisture.
All animals need protection from the sun
during the heat of the day. There is no shade in the desert, but there are little
crannies in the rocks where a small animal can find shelter. Some of the animals
go into underground burrows, where the air is a little cooler.
Not all land classified as desert
is equally arid. The driest parts may look very stony, but where there is more moisture
there will be more plants, such as sage brush, seasonal grasses, and small shrubs.
There may tree sized cacti, palo verde, and Joshua trees. These greener deserts may
be home to quail, pygmy owls, and even desert foxes and hawks. A few tertiary
consumers may be able to survive in these richer environments.
An interesting desert "extra"
is the oasis, a place where springs of water flow to the surface, providing an environment
where palm trees and shrubs may grow. Though rare, oases gladden the hearts of travelers,
and provide a refreshing micro-world with its own ecology.
A Food Pyramid in the Hot Desert Biome
© Elizabeth Anne Viau, 1999. This material may be used freely for instructional
purposes but not sold for a price beyond the cost of reproduction. Please inform
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