BACKGROUND:
In this exercise the students will write a
paragraph on an arthropod of their choice. They will try and find out
which arthropods have complete metamorphosis (like moths and butterflies),
incomplete (mosquitoes) or not at all. Complete goes through all the
stages (egg - larva (caterpillar) - pupa (covering stage) - adult. The example, of the butterfly and
moth is information on complete metamorphosis.
Moths and
butterflies belong to the group
called the Lepidoptera. They are medium to large sized insects with mouthparts
reduced to form a coiled tube for sucking liquid food. They have antennae that
are long and often feathery. They have large compound eyes with two pairs of
large and showy wings. Wings have overlapping scales and moths are often
hairy. The abdomen or stomach parts have ten segments. Butterflies which sleep
at night, have slim bodies and clubbed antennae and rest with wings folded
over their back, the hind wings almost covering the forewings. Moths, which
are awake at night, never have clubbed antennae and rest with the wings in
various positions.
Metamorphosis is a rapid transformation of
life that some animals undergo from juvenile stage to the adult form.
Metamorphosis is characteristic of amphibians but butterflies and moths also
undergo change due to hormonal control. The life of a butterfly is a little
different than that of a moth. Moths and butterflies go through four life
stages: egg, caterpillar, pupa, and adult. The length of the life cycle varies
from species to species.
Butterflies and moths both lay eggs which
hatch into caterpillars of different shapes and sizes depending on the
species. The caterpillar feeds usually on leaves and grows very rapidly. It
molts (sheds) its skin and develops a new one as the body grows. The
metamorphosis begins when the caterpillar uses silk to attach to a plant. The
skin hardens to form a chrysalis (for a butterfly) a cocoon for a moth. Within
the chrysalis and the cocoon the caterpillar changes to the butterfly and moth
respectively. In the adult stage the main purpose is to eat and to lay eggs.
Butterflies and moths usually only live for several weeks.
PROCEDURE:
- Read the Painted Lady and use the information at the end to go over
the difference between a butterfly and a moth.
- Discuss with students on doing a search on
arthropods using the internet to find out more about the different types.
Arthropods are the largest number of organisms on Earth, so the list can
be long. You may want the students to work together to find
the arthropod they want to find out how they metamorphoses.
- Instruct students to write a one paragraph report
after they do some research. This may be a homework assignment.
- Have each of the teams give an oral
report. Make a list of the different arthropods that are mentioned.
Common ones are ladybugs, flies, crabs, crayfish, spiders, and bees.
