Chap 17 Evolution and Diversity of Animals Flashcards
T/F Animals are extremely diverse?
True
How many known animal species?
over 1.3 million
Animals vary greatly in what?
size
habitat
body form
intelligence
What are the specific set of features common in all animals?
multicellular with eukaryotic cells that lack cell walls
heterotrophic, eating food by digestion
go through blastula stage of development
cells produce and bind to an extracellular matrix
Animal diversity reflects what?
shared ancestry
How many animal phyla are there?
9
What are the 9 animal phyla?
chordates echinoderms arthropods roundworms annelids mollusks flatworms cnidarians sponges
Animals are classified by?
having tissues
The first point on phyla split line distinguishes animals how?
animals with true body tissues and animals with no true body tissues
Which animal(s) has no true tissues?
sponges
What are simple animals?
sponges (porifera)
What are sponges?
aquatic and sessile (anchored to a surface)
they have hollow bodies that are either asymmetric of radially symmetric
After tissues how are animals classified?
by body symmetry and germ layer development
What are the types of symmetry?
bilateral
radial
no symmetry
What do bilaterally symmetric animals have?
cephalization
bodies have a head and tail
How are animals classified by germ layer development?
early in development animals undergo a process called gastrulation.
in some animals the gastrula only develops two tissue layers (endoderm and ectoderm).
in others, a third tissue layer (mesoderm) develops.
After germ layer development and body symmetry how are animals classified?
digestive tract
What are the types of digestive tract?
incomplete digestive tract
complete digestive tract
What are incomplete digestive tracts?
if the mouth both takes in food and ejects wastes
What are complete digestive tracts?
if food passes in one direction from mouth to anus
What are the simplest animals with true tissues?
cnidarians
What are cnidarians?
aquatic and radially symmetric
they have specialized cells that they use ti sting other animals
What are the four groups of cnidarians
jellyfish
hydra
coral
sea anemones
After bilateral symmetry and three germ layer development how are animals classified?
by mouth development
What are the two classifications of mouth development?
protostomes
deuterostomes
What are protostomes?
the gastrula’s first indentation develops into the mouth, and then the anus develops from the second opening
What are deuterostomes?
the gastrula’s first first indentation develops into the anus and then the mouth develops from the second opening
What are the simplest protostomes?
flatworms
What are flatworms?
(phylum Platyhelminthes)
bilaterally symmetric, with three germ layers.
What are three groups of flatworms?
planarians
flukes
tapeworms
After an animal is classified as a protostome and mouth development how are animals classified?
by segmentation
What is segmentation?
body is divided into repeated parts
What do segments do?
adds to the body’s flexibility and increases the potential for the development of specialized body parts
What phyla are segmented worms?
annelids
Annelids are characterized by what?
by body segments
a true coelom
a complete digestive tract
What are types of annelids?
terrestrial - earthworm and leeches
aquatic - polychaetes
Many ecosystems depend on what?
earthworms
What do earthworms do in ecosystems?
aerate and fertilize soils
Earthworms are more complex than they look and have a number of organ systems what are they?
complete digestive tract
closed circulatory system with aortic arches
nervous system that includes a brain and ventral nerve cord
excretory organs in each body segment
a saddle like thickening area that holds eggs in a specialized cocoon
Chordates are a diverse group of at least 60,000 species, including …?
humans
mammals
fish
other familiar animals
All chordates share what four features?
notochord
dorsal nerve cord
pharyngeal slit
postanal tail
Why do chordates share these features?
because they are inherited from a common ancestor
Vertebrates do what?
protect their spinal columns
What are vertebrae?
a series of small structures making up a backbone (can be made of bone or cartilage)
What were the first vertebrates to survive on land?
reptiles
About how long ago did reptiles evolve?
310-320 million years ago
How have reptiles adapted?
adapted to retain water inside their bodies and reproduce outside of it
Where do reptiles live and reproduce?
on dry land
During what age did reptiles dominate animal life?
the mesozoic era
What are the land adaptations acquired by reptiles?
reduced water loss from the skin due to scales
internal fertilization and amniotic eggs make reproduction independent of water
What are mammals?
warm, furry, milk-drinkers
About how long ago did mammals evolve?
200 million years ago
What traits do mammals have?
endothermic amniotes with milk-secreting mammary glands
Mammals also produce what, which helps conserve body heat?
hair
How are mammals grouped?
by reproduction
What do monotremes do?
lay eggs (similar to reptiles)
In marsupial and placental mammas, where do babies develop?
inside the uterus before birth
What do marsupial babies do?
continue to develop in pouches for many months
What do placental mammal babies do?
they are connected to the mother’s uterus and share her circulatory system
What tell the human evolution story?
fossils and DNA
Humans are in a group of placental mammals called?
primates
Primate features include what?
grasping hands with opposable thumbs
flat nails instead of claws
eyes set in the front of the skull, with binocular vision
brain is large in comparison with body size
