Chapter 10 part 2

What is the most successful animal group ever to live?

Phylum Arthropoda

How many named species are in Phylum Arthropoda?

Over 1 million named species

What fraction of all animals are arthropods?

About 2 out of every 3 animals

Approximately how many individual arthropods exist?

About 10¹⁸ individuals

Which animal group has more individuals than roundworms?

Arthropods

Where do arthropods live?

They inhabit all ecosystems

When did arthropods first appear?

Late Precambrian (~555 million years ago)

Which arthropod group is now extinct?

Trilobites

What is the size range of arthropods?

From 0.1 mm to 4 meters

What is an example of a very large arthropod?

Japanese spider crab

What feeding modes do arthropods use?

All modes of feeding

What is the most common feeding type among arthropods?

Herbivorous

Are arthropods vertebrates or invertebrates?

Invertebrates (no backbone)

What type of symmetry do arthropods have?

Bilateral symmetry (right and left mirror halves)

What does the term “jointed foot” mean?

Arthropods have jointed legs that allow flexible movement

What are appendages?

Jointed attachments such as legs, antennae, and mouthparts

Why are arthropod appendages important?

They allow movement, feeding, and sensing the environment

What type of skeleton do arthropods have?

An external skeleton (exoskeleton)

What is the function of the exoskeleton?

Protection, support, and prevention of water loss

Why must arthropods molt?

The exoskeleton does not grow, so it must be shed to allow growth

What does it mean that arthropods have segmented bodies?

Their bodies are divided into repeating sections

Why are segmented bodies important?

Segments are specialized for different functions

How do arthropods learn behaviors?

They rely on instincts

Can arthropods be taught or trained?

No, they have good instincts but cannot be taught

What does the flea circus image represent?

Arthropods appear skilled but act only by instinct, not learning

How many major classes are in Phylum Arthropoda?

Five major classes

What are the five major classes of Arthropoda?

Insecta, Arachnida, Crustacea, Diplopoda, Chilopoda

How many body sections do insects have?

3 body sections

How many pairs of legs do insects have?

3 pairs of legs (6 total)

How many pairs of antennae do insects have?

1 pair of antennae

What animals belong to Class Arachnida?

Spiders, scorpions, ticks, mites

How many body sections do arachnids have?

2 body sections

How many pairs of legs do arachnids have?

4 pairs of legs (8 total)

Do arachnids have antennae?

No antennae

What animals belong to Class Crustacea?

Crabs, lobsters, shrimp, crayfish

How many body sections do crustaceans have?

2 or 3 body sections

How many pairs of legs do crustaceans have?

5 or more pairs of legs

How many pairs of antennae do crustaceans have?

2 pairs of antennae

What animals belong to Class Diplopoda?

Millipedes

How many body sections do millipedes have?

Many body sections

How many pairs of legs per body segment do millipedes have?

2 pairs of legs per body segment

How many pairs of antennae do millipedes have?

1 pair of antennae

What animals belong to Class Chilopoda?

Centipedes

How many body sections do centipedes have?

Many body sections

How many pairs of legs per body segment do centipedes have?

1 pair of legs per body segment

How many pairs of antennae do centipedes have?

1 pair of antennae

Which arthropod class is extinct?

Class Trilobita

Why is the arthropod exoskeleton important?

It provides protection (armor) and a site for muscle attachment

Why must arthropods molt?

The exoskeleton does not grow, so it must be shed to allow growth

What type of digestive system do arthropods have?

One-way digestive system

Why is a one-way digestive system an advantage?

It allows efficient and continuous feeding

How is oxygen delivered in many arthropods?

Air is piped directly to cells

Why is direct air delivery an advantage?

It allows efficient respiration

How do sensory organs contribute to arthropod success?

They are highly developed and allow quick adaptation to environmental changes

Why does fast sexual reproduction increase success?

It allows rapid population

What is an exoskeleton?

An external skeleton not enveloped by living tissue

What are the main functions of the arthropod exoskeleton?

Protection and muscle attachment

What tissue secretes the exoskeleton?

The underlying epidermis

What material is the arthropod exoskeleton made of?

Chitin

What is chitin?

A polysaccharide that forms part of the hard outer integument of insects, arachnids, and crustaceans

Name some functions of modified exoskeleton structures.

Muscle attachment, energy storage, flying, sensory reception

Why must arthropods molt?

The exoskeleton does not grow and must be shed to allow growth

Why do arthropods crunch when stepped on or cracked when eaten?

Because of their hard exoskeleton

How is oxygen delivered in most arthropods?

Air is piped directly to cells

Why is this respiratory system efficient?

It is more efficient than most other invertebrates

What respiratory system do most insects have?

A tracheal system of air tubes

How do some arthropods breathe instead of using tracheae?

By gills

What limits arthropod body size?

The tracheal respiratory system

What senses are highly developed in arthropods?

Sight, touch, smell, hearing, balance, chemical reception

What main nervous system structures do arthropods have?

Brain, ventral nerve cord, segmental ganglia

What is the role of segmental ganglia?

Control movement and responses in each body segment

What type of circulatory system do arthropods have?

Open circulatory system

What is arthropod blood called?

Hemolymph

What color is hemolymph?

Colorless, pale yellow, or green

Can arthropod fertilization be external or internal?

Yes, it may be external or internal

How does fertilization usually occur in terrestrial arthropods?

Internally

How is sperm usually transferred in arthropods?

By mating

What do females usually do with sperm after mating?

Store it in a seminal receptacle

What is metamorphosis?

A change in form as an insect grows

How do insects grow?

By molting

What do both types of metamorphosis start with?

An egg

What is gradual (incomplete) metamorphosis?

Young insects look like small adults

What stage hatches from the egg in incomplete metamorphosis?

Nymph

How does a nymph compare to an adult?

Looks like the adult but without wings

How does a nymph become an adult?

By molting the exoskeleton several times

What are examples of insects with incomplete metamorphosis?

Grasshoppers, termites, cockroaches, dragonflies

What are the stages of incomplete metamorphosis?

Egg → nymph → adult

What is complete metamorphosis?

Larvae look very different from adults

How many stages are in complete metamorphosis?

Four stages

What hatches from the egg in complete metamorphosis?

Larva

What does the larva usually look like?

A worm-like form

What is the pupa stage?

A resting stage enclosed in a protective case where most growth occurs

What happens after the pupa stage?

The adult crawls out of the case

What are examples of insects with complete metamorphosis?

Beetles, butterflies, flies, ants

What are the stages of complete metamorphosis?

Egg → larva → pupa → adult

Which type of metamorphosis includes a pupa stage?

Complete metamorphosis

Which type has young that resemble adults?

Incomplete metamorphosis

Which type involves the most dramatic body change?

Complete metamorphosis

What type of metamorphosis does a butterfly undergo?

Complete metamorphosis

What are the four stages of complete metamorphosis in butterflies?

Egg → Larva (caterpillar) → Pupa (chrysalis) → Adult butterfly