An Exciting Educational Arthropod Adventure! Mr. Ellery Duncan Wealot (Mr. Wee) Presents… And an Animalia Adventure

Importance Arthropods are the most successful animals on the planet! They make up over 75% of known living and fossilized organisms. Some estimates count tens of millions of species on the planet. They have conquered…

Arthropods have been responsible for some of the most devastating plagues and famines known to man! (malaria, typhus, yellow fever, lyme disease, encephalitis, bubonic plague). We’re still bigger than they are. They also pollinate all of those pretty flowers!

Arachnida Scorpions Mites Spiders Ticks Main Classes Included:

Crustacea Crabs Lobsters (Slipper Lobster) Shrimp Pillbugs (roly poly)

Chilopoda (Centipedes) Diplopoda (Millepedes) Chinese Red Head Centipedes African Giant Millipede

Hexapoda (insects) The Bee The Mosquito The Ladybug Hissing Cockroach

Hercules Beetle

Trilobitomorpha Dominant marine animal 345 to 600 Million years ago. Extinct

Characteristics Characterized by: –Paired, jointed appendages Bilateral symmetry –Segmented bodies –Exoskeletons –Open Circulatory System –Dorsal brain and ventral nerve chord Greek: –Arthron-joint –Podos-foot

Jointed appendages Appendage- A part or organ, such as an arm, leg, tail, or fin, that is joined to the axis or trunk of a body Appendage- a limb or analogous part Appendage- a subordinate or derivative body part ff In arthropods, appendages are paired and have joints.

Smartness Check! How many appendages does Eduardo The Elephant have? I have 6 appendages!

Bilateral Symmetry A Mediterranean Jumping Spider

More Symmetry!

The Exoskeleton Reduces water loss Protects arthropods from the environment. Muscles are attached to the exoskeleton. In order to grow, arthropods must shed their exoskeleton (known as molting or ecdysis) –Immediately after a molt, they are very vulnerable because the exoskeleton needs time to harden.

Exoskeleton Structure Composed mainly of a modified form of chitin –A–A polysaccharide with Nitrogen –L–Lots of Hydrogen bonds Chitin is secreted from the epidermis. Exoskeleton is divided into plates –P–Points where plates separate create different segments of the body. Chitin Molecule

Circulatory System Open Circulatory system Hemocoelic Body Cavity- space between organs where blood flows 1 Big Dorsal heart pump with pores. –Blood goes in through the pores and is pumped to the brain.

–Like a spinal cord, but in invertebrates. –Bundle of nerves and ganglia No bones –Ganglia: mass of tissue Ventral Nerve Cord –In little insects, brain is often simply a mass of ganglia. A FLEA WITH A TINY BRAIN

A Life Lesson Life Cycle involves eggs, larvae, pupa (just certain insects), and adult. Egg Stage: –All arthropods, except scorpions, lay eggs. Larvae/Nymph Stage: –In some species, larvae are mini adults that grow bigger. Adult: Stinging Rose Caterpillar Spider Eggs Stinging Rose Adult

Making Babies Arthropods get very creative… Terrestrial: usually sexual Marine: Females usually lay eggs that are fertilized by the male. Parthenogenesis in some species. –Asexual –Growth and development of embryos occurs without fertilization. Millipedes making love:

Barnacles Barnacles are hermaphroditic crustaceans– they have both male and female reproductive organs. They still try to reproduce sexually whenever possible. But barnacles can’t move. They are also blind. So they have evolved to fight the odds…

Barnacles have a penis 8 times the size of their body. Proportionally, it is the largest penis in the animal kingdom. When a barnacle is ready to mate, it extends its penis into the water and feels around for another barnacle. Upon locating one, it inserts its penis into the ovum. Sperm, fertilization, and more barnacles follow.

Silverfish Insects, not fish. Mating involves the use of spermatophores: little waterproof packages of sperm. Mating: Upon meeting, the male and the female begin a ritualistic dance. This “mating dance” can last over half an hour. Eventually, the male releases his spermatophore onto the ground. The female picks it up via her ovipositor and fertilizes her eggs.

Other animals, such as arachnids, also release spermatophores. Many of them perform similar dances and rituals. Others just leave their packages on the ground and hope that the female will find them.

REVIEW Classes included: –Arachnids, crustaceans, millipedes, centipedes, insects. Characteristics –Paired, jointed appendages –Bilateral symmetry –Segmented bodies –Exoskeletons –Open Circulatory System –Dorsal brain and ventral nerve chord Terrestrial animals usually reproduce sexually. Marine Animals usually reproduce asexually. Life cycle: –Egg, larvae, sometimes pupa, adult

¡OOOH! ¡Ommatidia!

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