Download simple eye

• Arthropods most diverse group of
invertebrates. (1,130,000 species)
• 75% of all animal species
• jointed appendages are defining characteristic
that are adapted for walking, feeding, sensing,
and mating
• hard, thick, and made out of a
carbohydrate called chitin and
proteins.
• land arthropods must have a
waxy layer to protect against
water loss
• Molting = shedding of the old
exoskeleton
• also called ecdysis
• molts need to occur for
arthropod to increase in size
or add appendages
• new, softer exoskeleton
forms underneath old skeleton
• new exoskeleton will harden
overtime
•3 fused segments: head, thorax, and abdomen
• fusion allows for better movement and
protection
• some arthropods have a fused head and thorax
called a cephalothorax
Three types:
1. Gills
- aquatic
arthropods
2. Book lungs
- spiders,
horseshoe crab
- leaf-like plates
filled w/ air
3. Tracheal tubes
- terrestrial insects
- branching network of
hollow air passages
All respiration based
on diffusion of
gases!!
• Antennae detect movement, sound and
chemicals. Also used for communication.
• chemical odor signals can be given off
by the organism for communication as
well. Called pheromones.
• Most have one pair of
compound eyes and 3-8
simple eyes
• simple eye = one lens
used for detecting light
• compound eye = many
lenses, detect movements
of prey, mates, predators,
and colors
• Consists of 2 ventral nerve cords, anterior
brain, and several ganglia
• ganglia serve as control centers for specific
body sections
•Open system, blood pumped by one or more
hearts
• heart
vessels
tissues
(through open body spaces)
heart
• Complete gut
• mouth parts called mandibles
• adapted for chewing, holding,
sucking, or biting
• spiders have chelicerae, 1st
appendage adapted for
piercing or fangs
• arachnids and crustaceans
also have pedipalps, used for
holding food, sensing, and
even mating
• Use Malphigian Tubules
• located in abdomen
• empty into intestine
• Muscles attached to inner surface of
exoskeleton
• External in aquatic and internal for terrestrial
• some species exhibit parthenogenesis (form of
asexual reproduction in which a new individual
develops from an unfertilized egg.) ex. Bees, ants,
wasps