Evolution in the Animal
1. What’s the difference between a
chordate and an invertebrate?
l Chordates exhibit 4 characteristics during at
least one stage of life:
l Dorsal, hollow nerve cord, notochord, tail, and a
l Invertebrates = animals without backbones
l Chordates can be in 2 groups: chordates and
2. What type of body cavity do
most groups have?
l True coelom – a body cavity completely lined
with mesoderm (middle germ tissue layer)
3. Which invertebrate group has the closest
evolutionary relationship to chordates?
4. How is embryology of echinoderms
similar to that of vertebrates? What
might this similarity indicate about
their evolutionary relationship?
l Both deuterostomes
l Indicates they are
closely related, came
from common ancestor
5. Why would animals need to
adapt their formation of limbs?
l Each animal’s forelimbs is adapted to
survival in their particular environment
l Ex: ability to find and capture food, evade
predators, move through various types of
6. How is an animal’s body plan
like an “evolutionary experiment”?
l An animal starts the ‘evolutionary experiment’
with one type of body plan
l Over time, in order to survive and reproduce,
their body plan adapts
l Body plans that aren’t successful go extinct
l If successful, they will be able to survive and
7. Name 6 nonchordate invertebrates.
What were some of the 1st
characteristics that evolved in
l Sponges, echinoderms, arthropods, worms,
8. List 3 traits that arthropods
have that cnidarians do not:
l Bilateral symmetry
l 3 germ layers
l True coelom
9. Why do you think we don’t have
much fossil evidence of early
l Early invertebrates were tiny and soft-bodied,
making it nearly impossible to make a fossil
10. What characteristics have
evolved in fish?
l Bony skeleton
11. What characteristics have
evolved in birds?
l Hollow bones
l 2 legs covered
12. What characteristics have
evolved in reptiles?
l 4 limbs
l Amniotic egg
l Eggs don’t
develop in water
l Dry, scaly skin
13. What characteristics have
evolved in mammals?
l Four limbs
l Amniotic egg
14. Name the group of invertebrate
animals whose ancestors were related
to the earliest chordates.
15. What characteristic do reptiles
have that amphibians do not?
l Reptiles have lungs,
amniotic eggs, eggs
don’t develop in
water; dry, scaly skin
l Amphibians 1st stage
of life- no lungs, eggs
16. How have animals’ body plans evolved over time?
17. What pattern or relationship exists
between type of body symmetry and
the evolution of animals?
l Sponges – asymmetrical (no symmetry)
l Cnidarians – radial symmetry
l More advanced – bilateral symmetry
(*Exception – echinoderms)
18. What is the single most important
characteristic that separates birds
from other living animals?
l Although birds have defining characteristics
such as wings, beaks, four limbs, or ability to
fly, these characteristics are also found in
l The single characteristic separating birds
from other animals is FEATHERS
l This allows them to regulate their internal
19. Which two major groups of fishes
evolved from the early jawless fish and
still survive today?
l Early jawless fishes
fish - Sharks)
20. The evolution of jaws and paired
fins was an important development in
the rise of which group of animals?
21. List 2 ways that bony fish differ
from the other two fish groups:
l Bony fish:
1. Have bone
(Sharks don’t, jawless
2. Have jaws
(Jawless fish don’t)
22. What adaptation enables birds to
live in environments that are colder
than those in which most reptiles live?
l Feathers – can use to
regulate body temperature
23. How do nonvertebrate chordates
differ from other chordates?
l Nonvertebrate = no backbone
l Chordates includes vertebrates
l Therefore, not all chordates
have a backbone
24. What evidence exists to indicate
that annelids and mollusks are closely
l Levels of organization, body
symmetry, 3 germ layers, true
coelom, protostomes, and
25. The only animal to have an
asymmetrical body plan is:
26. Which of the worm groups has the
characteristic of a segmented body?
28. List the 5 types of animals
in Phylum Chordata
29. What was the 1 group of
animals to have cephalization?
30. What are 2 general characteristics
that ALL animals have?
l To be included in the Animal Kingdom, an
l Be multicellular
l Be heterotrophic (need food from others)
l Lack cell walls