phylum arthropods: class hexapoda

Q: What is the largest group of animals on Earth?

A: Insects (Class Hexapoda)

Q: What proportion of all named animal species are insects?

A: More than half of all named animal species

Q: How many insect species have been described in the USA and Canada alone?

A: 90,000 described species

Q: Approximately how many individual insects are alive at any one time?

A: Approximately one billion billion (10¹⁸ or 1,000,000,000,000,000,000)

Q: What is the primary habitat of insects?

A: Primarily terrestrial (land)

Q: What is a characteristic feature of insect body size?

A: Small size

Q: Why are insects considered the most successful animal group?

A: They have the most species, the greatest number of individuals, and have colonized nearly every terrestrial habitat

Q: What are the three body regions (tagmata) of insects?

A: Head, thorax, and abdomen

Q: How many pairs of antennae do insects have?

A: One pair of antennae

Q: What structures are found on the insect head?

A: Pair of antennae, modified mouthparts, and compound eyes

Q: What type of eyes do most insects have?

A: Compound eyes (made of ommatidia)

Q: Besides compound eyes, what other visual structures do many insects have?

A: Ocelli (simple eyes)

Q: What are modified mouthparts in insects?

A: Specialized feeding structures adapted for different diets (chewing, piercing, sucking, etc.)

Q: Do insects have both compound eyes AND ocelli?

A: Many insects have both types of eyes

Q: How many segments does the insect thorax have?

A: Three segments

Q: How many pairs of legs do insects have, and where are they located?

A: Three pairs of legs (one pair on each thoracic segment)

Q: How many pairs of wings can insects have?

A: One or two pairs of wings (or none)

Q: Which thoracic segments bear wings in insects?

A: The second and third thoracic segments

Q: What are insect wings made of?

A: Chitin

Q: What is a characteristic feature of insect wings?

A: Great diversity in structure and function

Q: What fills the insect thorax?

A: Muscles that control the legs and wings

A: Muscles that control the legs and wings

A: The abdomen (contains digestive, excretory, and reproductive organs)

Q: Why is the insect thorax so muscular?

A: It contains the muscles needed to control leg movement and wing flight

Q: Where does digestion take place in insects?

A: In the stomach (midgut)

Q: What structures are responsible for excretion in insects?

A: Malpighian tubules

Q: How do tracheae deliver oxygen to insect tissues?

A: Tracheae permeate (spread throughout) all tissues

Q: What are the three main internal systems described for insect organization?

A: Digestive system (midgut/stomach), excretory system (Malpighian tubules), and respiratory system (tracheae)

Q: Why must tracheae permeate all insect tissues?

A: To deliver oxygen directly to all cells, since insects don't use blood to transport oxygen

What are the key characteristics of Hexapods?

Mouthparts are mandibles; the body consists of three regions: a head with one pair of antennae, a thorax, and an abdomen; appendages are uniramous (unbranched)

What are examples of Hexapods?

Insects (beetles, bees, flies, fleas, true bugs, grasshoppers, butterflies, moths, dragonflies)