Download Arthropod Features

Section 1: Arthropod Characteristics
Arthropods have segmented bodies and tough exoskeletons with
jointed appendages.
Essential Questions
•
•
•
What is the importance of exoskeletons, jointed appendages, and
segmentation to arthropods?
What are some similarities and differences among the organ systems of
arthropods?
What are the methods used by arthropods to respond to stimuli?
Copyright © McGraw-Hill Education
Arthropod Characteristics
Vocabulary
Review
New
•
•
•
•
•
•
•
•
•
•
•
•
ganglion
Copyright © McGraw-Hill Education
thorax
abdomen
cephalothorax
appendage
molting
mandible
tracheal tube
book lung
spiracle
Malpighian tubule
pheromone
Arthropod Characteristics
Arthropod Features
•
Arthropods are segmented
invertebrates with bilateral
symmetry, coelomate body
cavities, and protostome
development.
•
Arthropods have
exoskeletons with jointed
appendages.
•
Between 70-85% of all
named animal species are
arthropods.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Arthropod Features
Segmentation
•
Segments can be fused into three main body regions: a head, thorax, and
abdomen.
•
The head has mouthparts, eyes, and often antennae.
•
The thorax is the middle body region to which legs and wings are
attached.
•
The abdomen is the posterior end of the arthropod and bears additional
legs, contains digestive structures and the reproductive organs.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Arthropod Features
Exoskeleton
•
•
•
•
Provides a framework for support
Protects soft body tissues and slows water loss
Provides a place for muscle attachment
Made of chitin
Copyright © McGraw-Hill Education
Arthropod Characteristics
Arthropod Features
Exoskeleton
•
Arthropods have paired, jointed appendages, which are structures that
extend from an animal’s body.
•
Adapted for a variety of functions, such as feeding, mating, sensing,
walking, and swimming.
•
Exoskeleton is made of nonliving material and cannot grow, so arthropods
must shed their old exoskeletons through molting.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Body Structures of Arthropods
Feeding and digestion
•
Arthropods have diverse feeding habitats and structures.
•
Many arthropods have a pair of appendages called mandibles that are
adapted for biting and chewing.
•
Arthropods can be herbivores, carnivores, filter feeders, omnivores, or
parasites.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Body Structures of Arthropods
Respiration
•
Arthropods obtain oxygen by using one of three structures :
• Gills- found in most aquatic arthropods
• Tracheal tubes – system of branching tubes that carry oxygen through
the body
• Book lungs – saclike pockets with highly folded walls, increasing
surface area for gas exchange
•
Both tracheal tubes and book lungs open to the outside through openings
called spiracles.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Body Structures of Arthropods
Circulation
•
Most arthropods do not rely on their
circulatory system to carry oxygen
•
Transports nutrients and removes wastes
Excretion
•
In most arthropods, cellular wastes are
removed via Malpighian tubules, which
connect to and empty into the gut.
•
Crustaceans and some other arthropods
do not have Malpighian tubules and
instead have modified nephridia.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Response to stimuli
•
Vision:
• A compound eye has many facets, which are hexagonal in shape.
• Each facet sees part of an image.
• The brain combines the images into a mosaic.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Response to stimuli
•
Hearing:
• Many arthropods have a sense organ called a tympanum, which is a
flat membrane used for hearing.
• Arthropod tympanums can be located on the forelegs, on the
abdomen, or on the thorax.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Response to stimuli
•
Chemicals
• Many insects communicate with pheromones – chemicals secreted by
many animal species that influence the behavior of other animals of
the same species.
• Give off signals related to feeding and mating
Copyright © McGraw-Hill Education
Arthropod Characteristics
Movement
•
The muscles are attached to the inner surface of the exoskeleton on both
sides of the joint.
•
The strength of muscle contraction depends on the rate at which nerve
impulses stimulate muscles.
Copyright © McGraw-Hill Education
Arthropod Characteristics
Reproduction
•
Most arthropods reproduce sexually.
•
Most arthropods brood or incubate their eggs, but do not care for their
offspring once they hatch.
Copyright © McGraw-Hill Education
Arthropod Characteristics