Section 30.4 (Exam 2) Flashcards
Arthropods Are the Most Abundant and Diverse Group of Animals
Arthropods are ecdysozoans with _______.
limbs
Name the 4 major arthropod groups.
Chelicerates
Myriopods
Crustaceans
Hexapods
Which 3 major arthropod groups have mandibles, and are called mandibulates?
Myriopods, crustaceans, and hexapods
Describe what tardigrades (water bears) and velvet worms have in common.
They are ecdysozoans with fleshy, unjointed appendages
What are trilobites?
Ancestors of arthropods with an abundant fossil record
They were the first to have jointed legs, and some of their appendages were modified for different functions
Name 3 groups of animals that belong to the arthropod group, chelicaerates.
Sea spiders, horseshoe crabs, and arachnids
What are some characteristics of chelicerates?
Two-part body
Head has two pairs of appendages modified into mouthparts, chelicerae; most have four pairs of walking legs
What are the two parts of a chelicerate body?
Cephalothorax and abdomen
What are chelicerae?
Present in chelicerates, two pairs of appendages that are modified into mouthparts.
Describe horseshoe crabs.
Changed very little over their evolutionary history – living fossils
Common in shallow marine waters along eastern North America and Asia.
Come into the intertidal zone in large numbers to mate and lay eggs.
Name all the different kinds of arachnids.
Spiders, scorpions, harvestmen (daddy long legs), mites, ticks
Describe the simple life cycle of arachnids.
Miniature adults hatch from eggs and begin independent life.
What is a common trait of mites and ticks?
Parasites of plants and animals
Describe spiders.
Predators; chelicerae inject venom into prey
Some have excellent vision for prey capture; others spin elaborate webs to snare prey
Name two myriapods.
Centipedes and millipedes
What are some shared features of myriapods?
Head and a long, flexible trunk with many pairs of legs
What differentiates centipedes and millipedes?
Centipedes—1 pair of legs per segment
Millipedes— 2 pairs of legs per segment (2 segments are fused)
Name the three groups crustaceans are divided into.
Decapods, isopods, and everything else
Name the decapod crustaceans.
Shrimps, lobsters, crayfish, and crabs
Name the isopod crustaceans.
Pill bugs
Name the crustaceans that aren’t isopods or decapods.
Amphipods, ostracods, branchiopods, copepods, and barnacles
Name the 3 crustacean and hexapod (insect) body regions.
Head, thorax, and abdomen
The head segments of crustaceans are _______ and they have 5 pairs of ______________.
fused; appendages
Thoracic and abdominal segments of crustaceans have _________ pair of appendages each.
one
What are the different functions that crustacean appendages can be specialized for?
Gas exchange, chewing, food capture, sensing, walking, and swimming
What is a crustacean carapace?
A fold of exoskeleton that extends over the head and thorax region
Hexapods have _______ legs.
six
Which two groups do hexapods include?
Insects and wingless relatives of insects
How many appendages are on the insect head?
One pair of antennae
How many appendages are on the insect thorax?
Three pairs of legs and two sets of wings in most groups
How many appendages are on the insect abdomen?
No appendages
Insects also undergo ________________.
metamorphosis
What is metamorphosis?
Substantial physical changes that occur between life stages.
What is the difference between incomplete and complete metamorphosis?
Incomplete metamorphosis: changes are gradual. Examples: grasshoppers and roaches
Complete metamorphosis: changes are dramatic. Examples: butterflies and moths
