Phylum Arthropoda Julie, Neema, Prachi Patel & Shiwani Desai

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

3 Classes

Insecta Ants 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