Animals are multicellular, heterotrophic Eukaryotes with tissues that develop from embryonic layers
animal bodies are held together by structural proteins such as collagen (nervous and muscle tissue are unique to animals)
most animals reproduce sexually with a diploid stage, usually dominating the life cycle
after a sperm fertilizes the egg, the zygote undergoes cleavage, leading to form a blastula
the blastula undergoes gastrulation, forming embryonic tissue layers and a gastrula
many animals have at least one larval stage. A larva is sexually immature and morphologically distinct from the adult stage, it eventually goes through metamorphosis
All animals have hox genes in which regulate the development of body form

what makes animals, animals:

ingest food instead of decompose
eukaryotic
motile
heterotrophic
contains a body cavity (coelom)
secrete extra cellular material (sponge: calcium, Jellyfish: gelatinous M.)

Organisms like sponges dont have tissue. Cleavage special type of division, the cells get smaller while the surface area increases. The hollow space is called a blastoceal. Gastrulation is invagination of the organism. The two holes are used as ingestion.The opening is called a blasotpore. Once you are able to see the blastopore, its no longer called blastula is now considered a Gastrula. A differentiation in tissue occurs ad endoderm forms.
Arthopods most abundant species on the planet. An embryonic form into larva (sexually immature organism) Morphologically distinct from the adult; it eventually undergoes metamorphosis. most animals have at least one larva stage
Hox Genes discovered in the late 70's early 80's, their major regulatory genes. Organized in the genome of the animal. Highly conserved (lots of similarities between different species)
Hox genes lay down the plan for growth or maturity.

Animals come form a long linage of organisms that date back over a billion years ago. Believed that we evolved from a protists. (choanflagulate)

The history of animals can be broken down up into periods. Paleonic (half a billion- a quarter of a million years ago) 540. million years ago, Cambian Explosion (explosion of life) Thought that Hox genes are responsible for this.

Devonian (the age of fishes) the most diverse vertebrate are fish.
Amphibian means 2 life
most animals that live in water fertilize externally
Reptiles are the first full time land vertebrae

During the Mesozoic era, dinosaurs dominated land. Invertebrates walked land first. Coral reefs began to emerge becoming niches for other organisms. Coral reefs have a lot of symbiotic relationships with organisms

Cenozoic is the period in which we live in now. Land plants, flowers and mammals, birds, insects become more diverse

Animals can be categorized by their symmetry in order to have the complexity, you have to form tissue. With tissue comes organization of the body plan.

radial symmetry means that the organism can be cut anywhere and both halves be identical
Bilateral meaning that the only identical halves are vertical cuts and not horizontal

Being bilaterally symmetrical

dorsal (top)
Ventral (bottom)
Right and left
Anterior (head)
Posterior (Tail)
Cephalization; development of the head

most organisms put there head into the environment first because that is where most of your nervous system attaches to

Adult tissue come from germ layer tissue. The ectoderm ultimately develops into skin and nervous system not the best system to tell you when something is internally wrong.
Endoderm is the innermost germ layer, organisms with two layers are diploblastic, and three are triploblastic

In triploblastic animals, a body cavity may be absent or present. A true coelom is derived from the mesoderm.
Coelomates are considered to be more complex than pseudo coelomates or a coelomates (flatworm) which has no body cavity

Protosomes which mean that the mouth is developed first, development is considered to be less on the complex side. Cleavage is spiral and determinate. Humans are deutrosomes which mean that they develop anus first and the cells are not determined. Also cleavage is radial.

points of agreements

common ancestry are shared among animals

sponges are basal animals
Eumatozoa is true tissued animals
most animals are bilateral
vertebrae and some other phyla are vertebrates

list of grades

Notochord
Brain
Head
Vertebrae
Jaws (Mineralizing Skeleton)
Lungs
Lobed FIns
Legs
Amniotic Eggs

CHORDATA
human phylum (Vertebrae is a subphylum) all Vertebrates are Chordata, but not all chordata are vertebrates. Have notochord (gelatinous brain structure), dorsal, and ventral side. on the dorsal of all chordates are a nerve chord, could be filled with fluid. (Echinoderms are more closely related to humans because they are deutrosomes) Pharyngeal slits or Clefts, and muscular post- annual tails.

NOTOCHORD
Longitudinal, flexible rod more of mesodermal structure, serves as a muscular system. Between the digestive tube and nerve cord

BRAIN
Tunicate
lacking a brain, only have the notochord during the larva stage, sassile, operates like a sponge in a way

Craiantes
Chordates that have heads share characteristics such as skull, brain, eyes, and other sensory organs located by the brain. Develop from the neural crest cells, evolved as least 530 million years ago during the cambrian explosion.

Vertebrates
about 52,000 kinds of vertebrates. Lamprey is the oldest living limb-rage of the vertebrates

Jaw
Mouth parts originated from the mineralization. The vertebral skeleton became mineralized much later. Gnathosome have true jaws evolved from skeletal support from the pharyngeal sit. enhanced sensory systems, including the lateral line system (found in fish), pared appendages, the extensively mineralized endoskeleton. Two groups of fishes that are categorized as partially minerals and fully, would be sharks.

The two types fishes are Cartilaginous and (boney) Osteocytes
The only difference between the two are the mineralized skeleton
(boney)They have air sacs on the side that allows them to float called swim bladder.

fish breathe by moving the water over their gills in chambers covered by a boney flap' operculum
Absolute most diversity about 400 million years ago

Biggest group of boney fish are Ray-finned fish simply because of the way their fins are shaped

There are fishes (shack heads) who have "lungs" in a sense becuase they could go to the surface and breath in air and use that for respiration

Lobed fins look more like armm most likely evolved so these bottom dwellers can move around without having to swim

Amphibians represent a group that has legs. Tetropods categorized because they have 4 legs. Ears for detecting air bourn sounds

In one lineage lobe fins become more relatively limb-like structurally

Amphibians are very sensitive species, they have thin skin and use their skin as respiratory station, meaning they dont have much resistance to drying out. Amphibian means two lives

Amniotic Eggs
all of the "metamorphosis" happens in an egg or in the matter for protection, to insure development
Amniotes are a group of heptopods whose living member are reptiles, birds, and mammals

Reptiles
Able to live on land for a while

Mammalian Clade

	Created by ridgeway.jeannet almost 11 years ago

Biology Note on Untitled, created by ridgeway.jeannet on 25/07/2013.

Untitled