Vertebrates and Invertebrates

Vertebrates and Invertebrates:

When the Platypus was discovered scientists weren't sure as to which group they should classify it into. The platypus was 
a poisonous furry animal with a duck's beak, beavers tail, otter's feet, lizard's skeleton shape and layed leathery eggs.
Scientists did agree that it was a vertebrate (Animals that have a backbone).
All vertebrates belong to the Phylum Chordata because they have a supporting rod which runs the length of their body.

Animals with no backbone are called invertebrates. Vertebrates and Invertebrates are divided into smaller groups.

The five vertebrate groups are:

Fish- Gills, Fins, Wet scales, External Fertilisation
Amphibian- Smooth skin, lungs/gills, External Fertilisation
Reptile- Dry scaly skin, Eggs with hard shells, Internal Fertilisation
Bird- Wings, Feathers, Eggs with hard shells, Internal Fertilisation
Mammal- Hair/fur on body, give birth to live young, feed young on milk, Internal Fertiliastion

External Fertilisation is when a female releases her eggs in the water where they're fertilised by adult male sperm
Internal Fertilisation is when sperm is placed inside the female so fertilisation takes place inside her body.

If an animal lays eggs it's oviparous.
If an animal gives birth to live young it's viviparous.

Some vertebrates are homeotherms which means they keep their body temperature constant and often warmer then their surroundings
by releasing heat from reactions in their body.

Some vertebrates are poikilotherms which means that their body temperature varies with the temperature of their surroundings.


Key Words:

Vertebrates
Chordata
Invertebrates
Fish
Amphibian
Reptile
Bird
Mammal
External Fertilisation
Internal Fertilisation
Oviparous
Viviparous
Homeotherms
Poikilotherms


Questions:

1. What is a backbone and what is it's purpose?
2. Why is the Platypus a Chordata?
3. How are reptiles and birds similar? How are they different?
4. What characteristic separates birds and mammals from other vertebrates?
5. Why was it difficult to classify the Platypus?


What you should've learnt:

Describe the main characterisitcs of the phylum chordata as animals with a supporting rod running the length of the body, an
example of this being the backbone in vertebrates.

Explain how scientists place vertetbrates into groups based on a. Oxygen absorpsion methods - lungs, gills and skin
b. Reproduction - internal or external fertilisation, oviparous or viviparous c. thermoregulation - homeotherms and
poikilotherms.

Demonstrate an understanding of the problems associated with assigning vertebrates to a specific group based on their
anatomy and reproduction methods and why many vertebrates are difficult to classify.