Chapter 33: Invertebrates

Question 1

Introduction

Answer 1

• Animals that lack backbone are called invertebrates
• account for 95% of animal species

Question 2

Sponges

Answer 2

• Belong to Phylum Porifera
• Lack true tissues, organs
• Suspension feeders
• Hermaphrodites – Male/Female

Question 3

​Cnidarians

Answer 3

• Belong to Phylum Cnidaria
• Clade Eumetazoa - True tissue
• Diploblastic, radial symmetry
• Two body plan
  
  • 1. Polyp
  • 2. Medusa

Question 4

2 Major Clades of Cnidarians

Answer 4

• 1. Medusozoa
  
  • members produce a medusa
• 2. Anthozoa
  
  • members only occur in polyps

Question 5

Medusozoans

Answer 5

• Has 3 Groups:
  
  1. Scyphozoans - true jellyfish
  2. Cubazoans - box jellies
  3. Hydrozoans - Hydra, Obelia

Question 6

Anthozoans

Answer 6

• Include sea anemones, corals
• hard exoskeleton of calcium carbonate

Question 7

Lophotrochozoa

Answer 7

• Clade characterized by
  
  • 1. Lophophore
  • 2. Trochophore larva
• Has six major phyla *

Question 8

Flatworms

Answer 8

• Belong to Phylum Platyhelminthes
• Include:
  
  • 1. Planarians
  • 2. Trematodes - flukes
  • 3. Tapeworms

Question 9

Rotifers

Answer 9

• Belong to Phylum Rotifera
• Reproduce by parthenogenesis
  
  • offspring from unfertilized eggs
• Some species lack males entirely

Question 10

Lophophorates

Answer 10

• Have crown of ciliated tentacles around mouth
• Used in suspension feeding
• Include phyla:
  
  • 1. Ectoprocta - “moss animals”
  • 2. Brachiopoda - “lamp shells”

Question 11

Molluscs

Answer 11

• Belong to Phylum Mollusca
• 2nd largest animal phlya
• Most have shell
• Body w/ 3 main parts
  
  • 1. Foot
  • 2. Visceral mass
  • 3. Mantle

Question 12

Molluscs cont…

Answer 12

• Include clades
  
  • 1. Polyplacophora - chitons
  • 2. Gastropoda
  • 3. Bivalvia
  • 4. Cephalopoda

Question 13

Chitons

Answer 13

• shell of eight dorsal plates

Question 14

Gastropods

Answer 14

• Most have singled, spiral shell

Question 15

Bivalves

Answer 15

• Shells in two halves, hinged

Question 16

Cephalopods

Answer 16

• Have well developed sense organs, brains

Question 17

Annelids

Answer 17

• Belong to Phylum Annelida
• Are segmented worms
• Groups include
  
  • 1. Leeches
  • 2. Earthworms

Question 18

Ecdysozoans

Answer 18

• Clade characterized by shedding of cuticle
• Process called ecdysis (molting)
• Two major phyla
  
  • 1. Nematoda
  • 2. Arthropoda

Question 19

Nematodes

Answer 19

• belong to Phylum Nematoda
• called roundworms; many parasitic members

Question 20

​Arthropods

Answer 20

• Belong to Phylum Arthropoda
• Probably 1 billion + species
• Body characteristics
  
  • 1. Segmented body
  • 2. Hard exoskeleton
  • 3. Jointed appendages

Question 21

Arthropod Anatomy

Answer 21

Question 22

Arthropods cont…

Answer 22

• Three major lineages
  
  • 1. Chelicerates
  • 2. Myriapods
  • 3. Pancrustaceans

Question 23

Chelicerates

Answer 23

• Include spiders, scorpions, ticks, mites, horse crabs
• Named after feeding appendages (chelicerae)
  
  • serve as pincers or fangs
• Head lacks antennae

Question 24

Arachnids (group of chelicerates)

Answer 24

• Bulk of chelicerates
• Six pair of appendages
• Spiders: construct silk webs

Question 25

Myriapods

Answer 25

• Include
  
  • 1. Centipedes
       * carnivores
       * poisonous claws
  • 2. Millipedes
       * feed on plant matter

Question 26

Pancrustaceans

Answer 26

• Newly formed clade
• Two groups
  
  • 1. Crustaceans
  • 2. Hexapods - insects

Question 27

Crustaceans (pancrustaceans)

Answer 27

• Include crabs, lobsters, shrimp, barnacles
• Two pair of antennae

Question 28

Hexapods (pancrustaceans)

Answer 28

• Over 900,000 species
• Head, thorax, abdomen
• Six legged - 3 pair
• 1 or 2 pairs of wings
• Undergo metamorphosis

Question 29

Deuterostomia

Answer 29

• Shares embryological characteristics
• Though primarily grouped by DNA
• Two major groups
  
  • 1. Echinoderms
  • 2. Chordates

Question 30

Echinoderms

Answer 30

• Belong to Phylum Echinodermata
• Slow moving, sessile
• Display radial symmetry as adults
• Include sea stars, sea urchins