Section 4: Insects and Their Relatives

Chapter 28: Arthropods

Section 4: Insects and Their Relatives

Insects and Their Relatives

The subphylum ______contains more species than all other groups of animals alive today

oIncludes centipedes, millipedes, and insects

oCharacterized by one pair of ______and appendages that ______

oAre thought to have evolved on land about ______

______

oInhabit almost every terrestrial habitat on Earth

Centipedes and Millipedes

Centipedes and millipedes are ______animals

These two classes of arthropods are quite similar in number

o______species of centipedes

o______species of millipedes

Centipedes and millipedes are characterized by a long, wormlike body composed of many leg-bearing segments

Because they lack closeable ______and a waterproof coating on their exoskeleton, their bodies ______

Thus they tend to live beneath rocks, in soil, or in other relatively moist areas

Centipedes

______

Have a pair of ______in their head region

oUsed to catch and stun or kill prey

Eat other arthropods, earthworms, toads, small snakes, and mice

Usually about ______long

Despite their name, which means 100 legs, centipedes may have from 15 to 170 pairs of legs

Each segment that makes up the body of the centipede bears ______of legs, except for the ______and the last ______

Millipedes

Each millipede body segment is formed from the fusion of two segments in the embryo and thus bears ______

Timid creatures that live in damp places under rocks and in decaying logs

Feed on dead and decaying plant material

When disturbed, many millipedes ______to protect their softer undersides

Some can also defend themselves by secreting unpleasant or toxic chemicals

Insects

More than ______insects

oNew ones are discovered in the tropics all the time

oExtremely varied in body shape and habits

oInsects are characterized by a body that is divided into ______parts – head, thorax, and abdomen – and has three pairs of legs attached to the thorax

oA typical insect has one pair of ______and one pair of ______on the head, two pairs of ______on the thorax, and uses a system of ______for respiration

Insects get their name from the Latin word insectum, meaning notched, which refers to the division of their body into three main parts

The essential life functions in insects are carried out in basically the same ways as they are in other arthropods

However, insects show a variety of interesting adaptations in ______, ______, and ______

Feeding

Three pairs of appendages that are used as ______

Can take on an enormous variety of shapes in species adapted to feed on different foods

Insect adaptations for feeding are not restricted to the shapes of the mouthparts

Many insects produce saliva that contains ______and helps break down food

Movement

Insects have three pairs of ______

oOften equipped with ______for holding onto things and for defense

oMay be adapted for functions such as jumping or capturing and holding prey

Along with birds and bats, insects are the only living organisms that are capable of ______

The flying ability of insects varies greatly

In flying insects, most of the space in the thorax is taken up by the large muscles that operate the wings

Insect Societies

Many animals form ______, which are collections of individuals of the same species that live together

Several types of insects are unique among invertebrates in that they form a special type of colony known as a ______

oSeparate individuals are dependent on one another for survival

______

These insects have developed complicated societies that may be composed of from half a dozen to more than 7 million individuals

Within such societies there is ______

oDifferent individuals perform the tasks necessary for the survival of the entire group

oThere are several types of individuals within insect societies

The basic types are:

o______

______

Lay eggs that hatch into new individuals for the society

______individual in the colony

o______

Fertilize the queen’s eggs

o______

Perform all the colony’s tasks except for reproduction

Insect Communication

All insects use sound, visual, chemical, and other types of signals for communication

Much of the communication done by nonsocial insects involves ______

Insects release chemical messengers called ______that affects the behavior and/or development of other individuals of the same species

Communication in social insects is generally more complex than in nonsocial insects

A sophisticated system of communication is necessary to organize a society

Each species of social insect has its own “______” of visual, touch, sound, and chemical signals that convey information among members of the colony

Pheromones are particularly important in insect societies

o______

o______

Also use “dances” to convey information

o______

o______

Chapter 28: Arthropods

Section 5: How Arthropods Fit into the World

How Arthropods Fit into the World

Arthropods play many roles in the natural world

oDirect food source for ______

o______of the world’s flowering plants depend on insects to pollinate them

oAgriculture would be impossible without the bees, butterflies, wasps, moths, and flies that ______

oBees manufacture ______

oSilkworms produce ______

oShrimp, crab, crayfish, and lobster are a large food source for humans

oMany useful ______can be obtained from arthropods

Not all arthropods are beneficial to humans

oInsects and arachnids cause billions of dollars in damage each year to livestock and crops around the world

oMosquitoes inflict annoying bites, and some species carry ______and ______

oTermites cause extensive damage to wooden structures

oFarmers have spent billions of dollars on poisonous chemicals to save their crops from these pests