Download Introduction to Animals Invertebrate Evolution and Diversity

Introduction to Animals
Invertebrate Evolution and Diversity
Chapter 25
Chapter 26.1
Introduction to Animals
Chapter 25
Characteristics of Animals
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Kingdom – Animalia
Multicellular
Heterotrophic
Eukaryotic
Lack cell wall
Types of Animals
• Invertebrates
–Lack backbone or vertebral column
–95% of animals
–Sea stars, worms, jellyfish, insects
•Chordates
Exhibit four characteristics during at least one
stage of life
– Dorsal, hollow nerve cord
– Notochord
– Tail that extends beyond anus
– Pharyngeal pouches
Lancelet
• Chordates with backbones = Vertebrates
–Fishes, amphibians, reptiles, birds,
mammals
What Animals Do to Survive
1. Maintain homeostasis by gathering and
responding to information
– Feedback inhibition
2. Obtain and distribute oxygen and nutrients
3. Collect and eliminate CO2 and waste
4. Reproduce
Animal Development
Animals have a wide variety of forms.
The following developmental factors determine the body plan:
 Levels of organization : cells, tissue, organ, organ systems
 Arrangement of Germ layers:
 differentiate into different tissue types:
• Endoderm (inner): digestive tract
• mesoderm (middle): muscles, blood
• ectoderm (outer): skin, nervous system
Development, cont.
 Overall Patterns of
Embryological
Development
– Protostomes
• Blastopore becomes mouth
• Most invertebrates
– Deuterostomes
• Blastopore becomes anus
• Chordates, Echinoderms
(sea stars)
Development, cont.
Body Cavity Formation
Coelom – completely lined with tissue derived
from mesoderm
Acoelom – lack a body cavity
Pseudocoelom – partially lined with mesoderm
Development, cont.
 Body symmetry:
• Radial
–body parts extend from a central point
–Divides into equal halves
• Bilateral
–Right and left sides are mirror images of each
other
–Distinct anterior and posterior ends and dorsal
and ventral sides
 Segmentation
– Repeating Parts
– Worms, insects, vertebrates
 Cephalization
– concentration of sense organs and nerve cells at
anterior end (head)
 Limb Formation
– Legs, Flippers, Wings
Cladogram of Animals
• Phyla defined by:
– Adult body plans
– Patterns of embryological development
• Ex. Phylum Arthropoda
– Body plan bilateral symmetry
– Segmentation
– Cephalization
– External skeleton
– Jointed legs
Invertebrate Evolution and Diversity
• Cladogram of invertebrates determined by
– evolutionary relationships among major groups
– sequence of evolution of important features
• Sponges
– Phylum: Porifera (“pore bearers”)
– Most ancient member of kingdom Animalia
– Multicellular, heterotrophic, lack cell walls, contain
few specialized cells
– Clade Metazoa
• Cnidarians
– jellyfishes, sea fans, sea anemones, hydras, corals
– Aquatic, soft-bodied, carnivorous, radially
symmetrical, stinging tentacles around mouths
– Simplest animals with body symmetry and
specialized tissues
• Nematoda (Roundworms)
– Unsegmented worms
– Pseudocoeloms
– Specialized tissues and organs
– Digestive tract with two openings
• Platyhelminthes
– Flatworms
– Soft
– Unsegmented
– Have tissues and internal organ systems
– Bilateral symmetry
– Cephalization
– Do not have coeloms
• Annelids
– earthworms, some marine worms, leeches
– Segmented bodies
– True coelom lined with tissue derived from
mesoderm
• Arthropods
– Phylum: Arthropoda – spiders, centipedes, insects,
crustaceans
– Bodies divided into segments
– Exoskeleton
– Cephalization
– Jointed appendages
• Mollusks
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Phylum: Mollusca – snails, slugs, clams, squids, octopi
Soft-bodied
Internal or external shell
True coeloms surrounded by mesoderm and complex
organ systems
– Free-swimming larva
• Echinoderms
– Phylum: Echinodermata – sea stars, sea urchins, sand
dollars
– Spiny skin
– Internal skeleton
– Water vascular system – used for walking and gripping
prey
– Five-part radial symmetry
Other Hexacorallia
Order:
Class:
Other Cnidaria
Phylum:
Sub-kingdom:
Kingdom:
Other invert.
Chordates
Animals
Hexacorallia
Cnidaria
Invertebrates
R. daphneae