Phylum Arthropoda

Julie, Neema, PrachiPatel

&Shiwani Desai

Definition: A phylum containing arthropods, an invertebrate animal having an exoskeleton, segmented body, and jointed appendages.

3 Classes

InsectaAnts

Butterflies

Bees

Flies

Crustaceans

Shrimp

Crabs

Lobsters

Arachnids

Scorpions

Spiders

Mites

3 Germ Layers

• Ectoderm Outermost layer of germ cells Develops into skin and nervous

tissue

• Mesoderm Middle layer of germ cells Connective tissue, bones,

muscles, and the circulatory system develop

• Endoderm Innermost layer of germ cells Lining of the digestive and

respiratory system

Symmetry• Bilateral the left and right sides of

the arthropod body are mirror images of one another

Coelom• A cavity lined by an epithelium

derived from the mesoderm layer. • Organisms that form inside the

coelom freely move, grow, and develop independently of the body wall.

• In arthropods it is reduced; consists only of a small cavity surrounding the reproductive excretory organs.

Cephalization• Cephalization- the concentration of sensory

tissues in the anterior part of the body (head).• Arthropods typically have highly sophisticated

heads possessing numerous appendages, sensory organs, their brain, and their mouth

Digestive Tract• The digestive tube is complete,

containing a mouth and anus. • The digestive tract varies greatly in

structure, depending upon the diet and feeding mode of the animal.

One example of a digestive tract with a mouth, and anus.

Grasshopper Digestive Tract Diagram

Segmentation• The embryos of all arthropods are

segmented• Built from a series of repeated

modules

Skeleton• Has an exoskeleton made from chitin• Serves as protection and provides

places for muscle attachment• Skeleton doesn’t grow with them

Pillbug shedding exoskeleton

Appendages• Jointed appendages antennae,

mouth parts, legs• Function as limbs• Some vanish or are highly modified

Circulatory System

• Open circulatory system– blood is pumped forward by the

heart, but then flows through the body cavity, directly bathing the internal organs

• Dorsal heart– belonging to, on, or near the back or

upper surface of an animal or organ

Dorsal view of the heart.

Respiratory System• Aquatic arthropods (crustaceans) possess

gills for respiration– Gills are outgrowths of the skin

• Terrestrial arthropods possess trachea and book lungs as respiratory organs– Book lungs- chambers with leaf-like plates for

exchanging gases

Respiratory System of a grasshopper

Reproduction• Some arthropods lay eggs and are noted

for prolonged maternal care• Some arthropods have organs of both

sexes• Due to presence of exoskeleton the growth

of an arthropod is periodical

Habitat• Worldwide– Deep sea– Coastal waters– Rivers and Streams– Land– Grasslands

FUN FACTS!!•About 84 percent of species known are arthropods•No two human beings have the same fingerprint; likewise, no two spider webs are the same.•A typical bed usually houses over 6 billion arthropods (dust mites)• Ants don't sleep•Each year, insects eat 1/3 of the earth's food crop.•Mosquitoes prefer children to adults, blondes to brunettes and their favorite color is blue