Geoscience Reference
In-Depth Information
Table 7-1.
Morphological and behavioral means of
animal adaptations for living in anaerobic wetland
environments. Based mainly on Mitsch and Gosselink
(2007).
Adaptation
Morphology or behavior
Special organs
Structures or regions for gas
exchange; i.e. gills (fi sh and
crustacea), parapodia
(polychaetes), breathing tubes
(insect larvae)
Improved oxygen
conditions
Means to improve oxygen
gradient across a membrane;
moving to oxygen-rich
environment or moving water
across gills by ciliary action
Internal structural
changes
Increased vascularization, better
circulation system, stronger heart;
to increase delivery of oxygen
Figure 7-1.
The African i sh eagle (
Haliaeetus vocifer
)
ranges over most of sub-Saharan Africa, where it
prefers fresh-water lakes and rivers. Okavango Delta
region, Botswana. Photo courtesy of M. Storm.
Respiratory pigments
Enhanced respiratory pigments to
improve oxygen-carrying capacity
Physiological
functions
Shifts in metabolic pathways and
heart pumping rate
Behavioral patterns
Decreased motor activity, closing
shell at night, moving with tides
or water level, etc.
crayi sh. Corals build hard reef structures upon
which the soft animals live. Invertebrates inhabit
fresh, brackish, and marine wetlands. They may
burrow into the soil or substrate, live on the soil
or plants, swim freely, or l y. In other words,
invertebrates exploit all types of niches within
wetland environments.
Figure 7-2.
African crocodile (
Crocodylus niloticus
), also
known as the Nile crocodile, seen here in a marsh of
the Okavango Delta region, Botswana. Hunted for
high-quality leather, the crocodile was on the brink of
extinction in the mid-twentieth century. Now protected
by national laws and international trade regulation, the
African crocodile has recovered. Photo courtesy of
M. Storm.
7.2.1 Insects
The insect class, as a group, is the most success-
ful of all animals; the number of known insect
species is about equal to the total of all other
species of plants and animals (Salsbury and
White 2000). Thus, it is not surprising that
insects comprise the largest and most diverse
group of wetland invertebrates, and they are
key parts of the food chains in most wetlands.
Insects have numerous adaptations for life on,
under, and above the water, and the ways in
7.2 Wetland invertebrates
Animals lacking backbones or internal skeletons
may be soft bodied, such as worms and jellyi sh
(see Fig. 5-18), or possess a hard exoskeleton.
The latter include myriad shelli sh
-
oysters,
clams, mussels, snails, crabs, shrimp, and
