Invertebrates

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9

Subphylum Myriapoda includes millipedes and centipedes

– Myriapods are terrestrial, and have jaw-like mandibles

Millipedes, class Diplopoda, have many legs

– Each trunk segment has two pairs of legs

Slide 81

millipede

Slide 82

Centipedes, class Chilopoda, are carnivores

– They have one pair of legs per trunk segment

Slide 83

Centipedes, class Chilopoda, are carnivores. They have one pair of legs per trunk segment

Slide 84

Insects

Subphylum Hexapoda, insects and relatives, has more species than all other forms of life combined.

They live in almost every terrestrial habitat and in fresh water.

The internal anatomy of an insect includes several complex organ systems.

Insects diversified several times following the evolution of flight, adaptation to feeding on gymnosperms, and the expansion of angiosperms.

Slide 85

Anatomy of a grasshopper, an insect

Abdomen

Thorax

Head

Compound eye

Antennae

Heart

Dorsal

artery

Crop

Cerebral ganglion

Mouthparts

Nerve cords

Tracheal tubes

Ovary

Malpighian

tubules

Vagina

Anus

Slide 86

Flight is one key to the great success of insects.

An animal that can fly can escape predators, find food, and disperse to new habitats much faster than organisms that can only crawl.

Slide 87

Many insects undergo metamorphosis during their development.

In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size.

Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar.

The larval stage looks entirely different from the adult stage.

Slide 88

Metamorphosis of a butterfly

(a) Larva (caterpillar)

(b) Pupa

(c) Later-stage

pupa

(d) Emerging

adult

(e) Adult

Slide 89

Most insects have separate males and females and reproduce sexually.

Individuals find and recognize members of their own species by bright colors, sound, or odors.

Some insects are beneficial as pollinators, while others are harmful as carriers of diseases, or pests of crops.