Lesson 10: Kingdom Animalia Phylum Chordata Flashcards
Phylum Chordata
Most organisms are vertebrates. They have a bony skeleton and
backbone.
However there are two groups of invertebrates included in the
phylum Chordata because they share the 3 key features of all
chordate animals.
4 subphyla
Key Features of Phylum Chordata
A dorsal nerve cord which branches to all parts of the body.
A notochord (rod of cartilage), which runs along the dorsal
length of the body.
Occurs only in the embryo in vertebrates ( a backbone of
cartilage or bone replaces the notochord)
Gill slits in the pharynx (throat).
In terrestrial vertebrates the gill slits occur only in the embryo.
Subphylum Urochordata
Tunicates (sea squirts)
Invertebrates
Subphylum
Cephalochordata
Lancelets
Invertebrates
Subphylum Agnatha
Jawless fishes such as hagfish
and lampreys.
The oldest group of vertebrates
Only about 60 species exist
today
Smooth, tube-shaped fishes
can grow up to one metre long.
Scavengers or parasites
Subphylum Gnathostomata
Jawed chordates
Vertebrates
6 classes
Class Chondrichthyes
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Aves
Class Mammalia
Class Chondrichthyes
There are about 850 species
of sharks, rays and skates
Have a skeleton of cartilage
rather than bone and 5-7 gill
slits (lack the gill covers that
are characteristic of bony
fish)
Class Osteichthyes
About 20 000 known species of bony
fish.
Have a skeleton of bone
Most of the fish species are called
ray-finned fishes( have scales formed
from bone).
The ancestors of the first land –living
vertebrates were the lobe-finned
fishes (fleshy fins supported by limb
like bones)
There are 6 species of lungfish
and one species of coelacanth in
existence today
Class Amphibia
Means “dual-life” in reference to
the fact that the 4000 species of
the class amphibia start life as gill
breathers but spend their adult life
as lung breathers
Depend on external sources of heat
to regulate body temperature
Have a 3 chambered heart, smooth
scale-less skin and eyelids.
Limbs are adapted for walking on
land and can produce sound from
their larynx
Class Reptilia
Most of the 6000 species of
the class reptilia live in
deserts and tropical areas
Have better developed lungs
than amphibians and a rib
cage to protect them
Have a thick scaly skin made
from Keratin (also a key
component of feathers,
fingernails and hair)
Class Aves
The key feature that distinguishes the
9000 species of the class Aves is feathers.
Feathers are a modified form of reptile
scales. They also share body shape, leg
scales, clawed toes and shell covered
eggs.
Unlike reptiles, birds, generate and
maintain their own internal body
temperature.
Most structural features are related to
flight
Hollow bones
System of air sacs in their bones
allow them to move air in only one
direction
Class Mammalia
Distinguished from other
vertebrates by the presence
of hair and milk producing
mammary glands.
Most give birth to live young
Most live on land (exceptions
include dolphins and whales)
Have lungs and a four
chambered heart.
