Arthropods

Trilobites

Trilobites

extinct marine arthropods that lived from the Cambrian to the Permian period. They had a hard, segmented exoskeleton and are one of the earliest known groups of arthropods.

Crustaceans

diverse group of arthropods that primarily live in aquatic environments. This group includes familiar animals like crabs, lobsters, shrimp, and barnacles. They typically have a hard exoskeleton and two pairs of antennae.

Chelicerates

subphylum of arthropods that includes spiders, scorpions, ticks, and horseshoe crabs. They are characterized by having specialized mouthparts called chelicerae, which are often used for feeding and defense.

Insects

class of invertebrates within the arthropod phylum. They are characterized by having a three-part body (head, thorax, and abdomen), six legs, and typically one or two pairs of wings. Insects are incredibly diverse and include species like ants, bees, beetles, butterflies, and flies.

Myriapods

Myriapods are a group of arthropods that includes centipedes, millipedes, and their relatives. They are characterized by having elongated bodies segmented into numerous pairs of legs. Unlike insects, myriapods typically have numerous legs per body segment.

The three main features of an arthropod’s body are the ______ made of chitin; a series of paired, jointed ________, and segmented ______ parts.

exoskeleton, appendages, body

Chitin is a long organic molecule made of _____________. Chitin is arranged in layers.

carbohydrates

Choose three reasons why jointed appendages are considered an important adaptation during the evolution of arthropods.

a. They allow for growth.

b. They allow for movement.

c. They allow for segregation. 

d. They are used for digestion.

e. They are used for sensing.

f.They are used to manipulate or chew food.

b, e, f

Trilobites

• Marine arthropods that are now extant / extinct

• Most were bottom / surface feeders.

extinct, bottom

Crustaceans

Found in ______, in ______, and on land

examples?

oceans, in freshwater streams, and on land

examples: lobsters, pill bugs, barnacles

Chelicerates

Have specialized daggerlike mouthparts / segmentation used to tear food

examples?

mouthparts

examples: Horseshoe crabs, spiders, mites, ticks

Insects

Account for 80 percent of all known animal / arthropod species

• Most are terrestrial and have
six / eight legs.

examples?

arthropod, six

examples: Ants, moths, bees, flies

Myriapods

Long bodies with few / many pairs of legs

•Live in dry / moist environments

many, moist

examples: centipedes, millipedes

three important body functions that are made difficult by the presence of an exoskeleton.

a. feeding

b. moving

c. growing

d. reproducing

e.secreting enzymes

f. maintaining internal and external equilibrium

c, d, f

An arthropod’s cuticle cannot grow along with the animal. Therefore, an arthropod sheds its exoskeleton in order to grow. This process is called _______

molting

The animal secretes a new layer of cuticle underneath / on top of its existing exoskeleton.

underneath

The animal secretes enzymes / sugars that begin to digest and weaken the old cuticle, allowing the exoskeleton to dissolve / split open and the animal to crawl out of it

enzymes, split open

The new exoskeleton is filled with air / fluid while it is still soft, making the animal larger than it was before the molt.

fluid

Arthropods and vertebrates have different circulatory systems. An arthropod has a(n) open / closed circulatory system and a vertebrate has a(n) open / closed circulatory system.

open, closed

An arthropod senses its surrounding environment using two body parts: ___________ and ______________

antennae, compound eyes

A mammal’s eye has only one lens, but an arthropod’s eye, which is called a _______ eye, has thousands of tiny individual lenses. Each lens interprets only a small portion of the field of view.

compound

The two species that scientists think are the closest relatives to arthropods are _________ and onychophorans ___________

annelids (segmented worms), onychophorans (velvet worms)

The four main features of a crustacean’s body are (i) two distinct body sections, (ii) a hard ________, (iii) two pairs of _________, and (iv) one pair of appendages on each _________

carapace, antennae, segment

This body section is the region of an organism in which the head and trunk region are combined into one long section.

cephalothorax

This body section refers to the rear portion of the organism.

abdomen

This shield-like section of cuticle covers the sides of the body and protects the gills.

carapace

A crustacean may use its claw to collect and manipulate food / tools, to club its prey while courting / hunting, to attract females / prey, or to mark / block the entrance to its shell.

food, hunting, females, block

A crustacean uses its antennae to eat / smell food, to locate / protect mates, and to avoid / attract predators.

smell, locate, avoid

Mandibles are highly adapted appendages that a crustacean uses to crush and bite / ingest and digest food.

bite

A crustacean uses two body parts to move: ____ and _________.

legs, swimmerets

has a flattened body and seven pairs of legs

isopod

has five pairs of jointed appendages (ten legs)

decapod

is a parasite that lives in the lungs and nasal passages of vertebrates.

tongue worm

is a sessile filter feeder wrapped in a calcified shell.

barnacle

A chelicerate is an arthropod that lacks _____ and _______ and has six pairs of _________

antennae, mandibles, appendages

Arachnids have _______ legs, fanglike pincers that inject ______, and the ability to produce a material called _______.

eight, venom, silk

tiny holes on the abdomen that open and close to allow oxygen to enter

spiracles

structures built of many thin, hollow sheets of tissue

book lungs

tubes that carry oxygen directly to the arachnid’s tissues

tracheae

excretory structures that allow spiders to minimize loss of water while excreting metabolic wastes

Malpighian tubules

Silk is produced in a spider’s abdomen / tracheae.

abdomen

Circle all of the following that are uses of a spider’s silk.

a. attracting mates

b. building shelters

c. building webs

d. producing drag lines

e. sensing air temperature

f.wrapping prey and egg cases

b, c, f

mites

pest species that negatively impact cropland

scorpions

inject venom from a stinger at the end

spiders

inject venom from a stinger at the end of their tail

ticks

can transmit serious human diseases

________ are tiny holes in an arachnid’s abdomen that open and close to let oxygen enter, allowing the arachnid to breathe.

spiracles

Insects are considered an incredible success story, because they have moved into virtually every ecological ____________ and can be found in the most extreme __________

environment, environments

Incomplete metamorphosis is a pattern of development in which the insect looks like a miniature adult / larva when it hatches. The immature insect, called a nymph / pupa, gets larger with each molt and grows / sheds wings and sexual organs during later molting stages.

adult, nymph, grows

During a metamorphosis, an organism changes form as it develops from a _____ into an ____

larva, adult

With complete metamorphosis, an insect’s form changes entirely from a larva to an adult. With incomplete metamorphosis, the larva is a miniature version of the adult and grows larger in size by molting.

complete, incomplete

Arthropods compete with humans for resources, because many arthropods are _________ that feed on plants that humans use for food, textiles, and building materials.

herbivores

An insecticide is a chemical compound that ______ insects and other arthropods.

kills

negative effects of insecticides

a. Insecticides are poisonous and may harm other animals, including humans. 

b. Some insecticides do not break down quickly and may accumulate in the food chain through biomagnification.

c. Arthropods can become resistant to an insecticide through natural selection, so the insecticide is no longer effective.

arthropod-specific insecticides

only impacts a specific type of arthropod

integrated pest management

non-synthetic methods such as
traps, barriers, and introduced predator species

genetically modified plants

engineered to be resistant to certain pest species

A ______ is an organism that carries a disease from one host to another.

vector