f01u4p2 - Unit Four Insects Unit IV Insects A major portion...

Unit Four
Insects
 Project Oceanography Fall 2001
55
Unit IV Insects
A major portion of the information for this unit was obtained from “The guide to
the Common Aquatic Invertebrates of the Loxahatchee Basin”
by Carlos L. de la Rosa, Ph.D. and Carlos A. de la Rosa
On the cutting edge…
Scientists at Brooker Creek Preserve are on the cutting edge of science using
biological indicators to survey the health of the ecosystem and its watershed
area. In addition to using the latest electronic sensors to measure water quality,
scientists can verify their results by studying the health of biological indicators. In
this case, by looking at aquatic insects in the various preserve habitats,
researchers can tell if the food webs are still intact.
Aquatic Insects
Lesson Objectives: Students will be able to do the following:
• Categorize aquatic insects with regard to their habitat
• Describe the functional trophic groups of aquatic organisms
• Distinguish between complete and incomplete metamorphosis
Key concepts: insect, macrohabitat, microhabitat, functional trophic group,
complete metamorphosis, incomplete metamorphosis
Insects and their Habitats
Insects are one of the largest
groups of organisms on earth. Only
about one million species have been
identified of the one billion estimated
to exist. Their three distinct body
regions, six legs,
and sometimes
wings identify
insects. The three
body regions
include: the head,
the thorax , and
abdomen . The head contains the
mouthparts and most of the sensory
organs. The thorax provides the
attachment area for the three sets of
legs and if present the wings. The
abdomen mainly functions in
digestion, respiration, and
reproduction. Insects also have a
tough exoskeleton that protects them
from natural enemies and extreme
changes in environmental conditions.
Insects have interesting internal
adaptations designed to suit their
lifestyles. For instance, insects have
open circulatory systems that allow
the blood to move around inside the
body cavity without being enclosed
in blood vessels. This helps to more
efficiently distribute oxygen and
nutrients to all body parts. Insects
breathe using openings on the body

Unit Four
Insects
 Project Oceanography Fall 2001
56
called spiracles . Air enters the body
through these holes and is
distributed throughout the insect’s
body. Insects that eat have digestive
systems that are long tubes divided
into parts for different functions. The
insect nervous system transports
information from the sense organs
such as the antennae and eyes to
the brain for processing. Other
information is processed at nerve
centers throughout the body.
Insects can also be categorized and
classified in other ways. Scientists
classify organisms by studying
similarities and differences in their
appearance (including shape, size,
color, etc.) They also study
behaviors, life cycles , and other
characteristics. For instance, insects
can be divided into two large groups:
those found in aquatic environments
and those found in terrestrial
environments. These large