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Chordates
Nerve Cords and Spines
Chordata means corded
Everything in the phylum chordata have a dorsal (back side) nerve cord (called a
notochord) running from one end of the body to the other.
Grouped with Echinoderms?
Remember the chordates are
grouped with the
echinoderms because of the
way they develop after being
a fertilized egg.
Symmetry
All chordates have bilateral symmetry. Usually well defined with the nerve cord
centered as a dividing line.
Environment
Chordates live in
nearly every
environment on
Earth. The different
classes are more
specialized for
specific types of
biomes.
Chordates vs Vertebrates
Most of the chordates are also vertebrates. That means the notochord actually
develops into a bone covered spine.
Endoskeleton
The vertebrates all
have an endoskeleton.
Endo means inside, so
it is the bones that
support the body,
protect it, and give
places for muscle to
attach.
Homeostasis
Because the chordates usually
have complex bodies with complex
brains, it is important that they
keep their body temperature at a
specific (depending on the species)
range of temperatures.
Homeostasis is the process that
animals use to keep their bodies in
balance. Temperature
maintenance is one of the most
important factors of homeostasis.
Warm and Cold Blooded?
The terms warm and cold blooded
are often used to describe how
animals maintain their body
temperatures, but they cause a lot
of misnomers.
Warm or Cold Blooded?
Warm or Cold Blooded?
Homeotherm or Heterotherm!
A better set of terms than warm
and cold blooded is homeotherm
or heterotherm.
Homeotherms can maintain their
own body temperature.
Heterotherms regulate their body
temperature using the
environment.
Reproduction
Nearly all chordates reproduce sexually. Very often there is obvious sexual
dimorphism.
Classes of Chordates
Agnatha or Jawless Fish
Like all fish, the
agnatha are aquatic
getting their oxygen
from the water.
Agnatha
The agnatha have no scales, a skeleton made of cartilage, and no jaw.
Chondrichthyes (Cartilaginous Fish)
The sharks, rays and skates like
the agnathes have a skeleton
made of cartilage. Unlike the
agnathes though, they have much
more developed senses, organs,
and jaws allowing them to bite to
catch their food.
Chondrichthyes (Cartilaginous Fish)
It is true that some sharks must
swim in order to push water past
their gills, but that is not true of ALL
sharks and rays.
Chondrichthyes (Cartilaginous Fish)
Sharks, skates and ras have highly developed sense organs including ampullae of
lorenzini that can detect the bioelectrical signals of other animals.
Osteichthyes (Bony Fish)
The osteichthyes
are the first
animals that we
see that have a
true bone
endoskeleton.
Osteichthyes (Bony Fish)
They also have
scales, gill flaps
that allow them to
circulate water to
breath, and a swim
bladder that gives
them buoyancy.
Osteichthyes (Bony Fish)
Like the other fish
classes, they are
mostly egg layers
and mostly
heterotherms (cold
blooded).
Amphibians
Amphibians are
the first group of
chordates that
can breath air.
Most amphibians
start off as
aquatic animals
with gills before
undergoing a
metamorphosis
during which they
develop lungs.
Amphibians
Amphibians also
have a three
chambered heart,
excellent vision,
skin that they can
absorb water and
oxygen through,
ears, and a
strong muscle
and skeleton
system.
2 Main Groups
With tails as adults or without tails
as adults.
All are heterotherms, carnivores,
and reproduce by laying large
amounts of soft eggs.
Reptilians
Many reptiles are
able to live in land or
even in very dry
environments largely
because they have
very well developed
lungs and skin
covered in protective
scales.
Reptilians
Most reptiles lay
eggs. Those eggs
have a protective
shell.
Reptilians
Reptiles also have a
highly developed
kidney that allows
them to filter their
blood very efficiently
saving them water.
Reptiles
Lizards
Reptiles
Turtles
Reptiles
Crocodilians
Reptilians
Snakes
Reptilians
How many deaths by snake in the U.S.?
2016: 1 by rattlesnake
2016: 1 by rattlesnake
2015: 6, 4 by rattlesnake (one was a snake handler), 1 by cottonmouth, 1 by pet
cobra
2016: 1 by rattlesnake
2015: 6, 4 by rattlesnake (one was a snake handler), 1 by cottonmouth, 1 by pet
cobra
2014: 3 by rattlesnake (one was a pet) (one was a snake handler)
2016: 1 by rattlesnake
2015: 6, 4 by rattlesnake (one was a snake handler), 1 by cottonmouth, 1 by pet
cobra
2014: 3 by rattlesnake (one was a pet) (one was a snake handler)
2013: 2 by rattlesnake
2016: 1 by rattlesnake
2015: 6, 4 by rattlesnake (one was a snake handler), 1 by cottonmouth, 1 by pet
cobra
2014: 3 by rattlesnake (one was a pet) (one was a snake handler)
2013: 2 by rattlesnake
2012: 1 by pet, 1 by rattlesnake (snake handler), 1 by copperhead...actually by
heart attack the day after being bitten so the copperhead likely was NOT the
cause of death as the internet tried to report.
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
Killed by cars?
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
Killed by cars? 166,526
Killed by dogs?
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
Killed by cars? 166,526
Killed by dogs? 192
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
Killed by cars? 166,526
Killed by dogs? 192
Killed by pythons and boas?
So in the last 5 years, 7 people in the United States were killed by venomous
snakes in the wild.
Killed by cars? 166,526
Killed by dogs? 192
Killed by pythons and boas? 0
Copperhead Population:
Estimated over 100,000
Cars: 7.5 Million
Dogs: ~1.5 Million
What’s the scariest?
Avians
Birds have
feathers, a
four
chambered
heart, are
homeotherms
(warm
blooded), and
lay eggs.
Avians
Birds also usually take care of their young and have advanced social structures.
Avians
Not all birds fly, but they have low density skeletons which make their bodies
much lighter.
Mammalians
Mammals are
homeotherms,
have four
chambered
hearts, grow fur,
usually develop
in the mother,
and are fed with
milk from
mothers.
Mammalians
Mammals
have
specialized
teeth.
Mammalia
Fur can be modified.