12-1 What is a Vertebrate?
Objective
1. Describe the characteristics of chordates and
vertebrates and how they control body
temperature
2. Explain how scientists have been able to infer the
relationships of major groups of vertebrates
Chordates (Chordata
phylum)
All have had or have notochord, a nerve cord in back, and
slits in the throat area
- most are vertebrates (fish, amphibian, reptiles,
mammals), but some are invertebrates (lancelets)
Notochord
phylum name Chordata comes form the notochord which
is the flexible rod supporting a chordate’s back
- lancelets have a notochord forever
- vertebrates develop a backbone
Nerve Cord in Back
all have nerve cords, some have it down the back and
others do not (worms, arthropods)
- e.g. spinal cord
- sends messages throughout the body because the
brain and nerves are connected
Slits in the THroat
pharyngeal slits
- most vertebrates don’t have it at birth
- fishes have it as part of their gills
Vertebrates
have all characteristics of chordates but in addition have
an internal skeleton and part of it is a backbone
supporting the body and its movements
Backbone
spine
- formed by vertebrae (plural), vertebra (singular)
- vertebrae are lined up in a row on top of one
another with joints in between allowing movement
and flexibility of the spine
- vertebrae has a hole in it and in it is the spinal cord
Internal Skeleton
endoskeleton made up of the backbone, skulls and ribs
- gives the body its shape and framework so muscles
can attach to it
- protection of internal organs (skull protects brain)
- grows along with the animal so animals with
endoskeleton grow larger than those with
exoskeleton because of the support it provides
Vertebrate Evolution
studying fossils and other evidence helps scientists make
inferences about the relationships between major groups
of vertebrates
- first were probably fishes which first existed over
500 million years ago
- fishesamphibiansreptilesmammals and birds
Differing
Characteristics
major difference=control of body temperature
- body temperature is close to the environment’s
temperature fishes, amphibians, reptiles
- body temperature is different than the
environment, body is stable and warmer birds and
mammals
- Ectotherms (fish, amphibian, reptiles): body doesn’t
produce a lot of internal heat so it changes
depending on the environment (aka. Coldblooded,
although the blood is warm)
- Endotherms (mammals): body controls its own
temperature, body temperature doesn’t change a
lot (maintains body temerpature), have sweat glands
so they can sweat (we are cooled by sweating when
our sweat evaporates), fur keeps them warm
Homework
12-1 Assessment (Red Group 12-1 NTG)