Download - CHARACTERISTICS OF ANIMALS: WELCOME TO YOUR KINGDOM! Adapted from Kim Foglia - April 2015
CHARACTERISTICS OF ANIMALS: WELCOME TO YOUR KINGDOM!
Adapted from Kim Foglia - April 2015
ANIMALS
Invertebrates
(animals without a backbone)
PoriferaCnidariaWormsMollusksEchinodermsArthropods
ANIMALSV
ertebrates (
animals with backbones)
FishAmphibiansReptilesBirdsMammals
CHARACTERISITCS OF ALL ANIMALS:
1. Eukaryotic2. Heterotrophic (ingestive)3. Multicellular/differentiated cells4. Cells have NO cell walls5. Movement (at some point in
lifespan)6. Reproduction (Most sexual)
Porifera
Cnidaria
Platyhelminthes
sponges jellyfish flatworms roundworms
Nematoda
Mollusca Arthropoda Chordata
Annelida Echinoderm
mollusks
multicellularity
Ancestral Protist
tissues
bilateral symmetry
body cavity
segmentation
ANIMAL EVOLUTION
eucoelom
starfish vertebrates
endoskeleton
segmentedworms
insectsspiders
backbone
LIFE ON EARTH
EMBRYOLOGY
REPRODUCTION•M
ost animals reproduce sexually•D
iploid stage usually dominates life cycle•H
aploid stage characterized by sperm and eggs produced by meiotic division
•In most animal species, a small flagellated sperm fertilizes a larger non-motile egg, forming a zygote
DEVELOPMENT•T
he zygote then undergoes cleavage, a succession of mitotic cell divisions with no cell growth between divisions
•Cleavage leads to a multicellular (usually hollow) ball called a blastula
•Blastula goes through gastrulation – the layers of embryonic tissues that will become adult parts are produced
•Result is a gastrula
•Some animals, including humans, develop directly into adults
•Most animals include a larval stage
•Larva – sexually immature form of the animal that is:morphologically different from adultEats different foodOften has a different habitat
•Larvae go through metamorphosis to juvenile stage that resembles adult
EMBRYONIC DEVELOPMENT
HISTORY OF ANIMALS SPANS MORE THAN ½ BILLION YEARS
• The animal kingdom includes the greatest diversity of living organisms
• Has an even greater diversity of extinct ones; ~99% of all species that have ever lived are now extinct
• Scientists estimate that the common ancestor of living animals lived sometime between 800 and 675 mya
ANIMALS CAN BE CHARACTERIZED BY BODY PLANS
•Despite the diversity in morphology, animals share a relatively small number of “body plans”
•Body plan – particular set of morphological and developmental traits, integrated into a functional “whole”
SYMMETRY•A
basic feature of animals is their type of symmetry – lack of it
•Asymmetrical (sponges)
•Radial symmetry: revolves around an axis (sea anemone)
•Bilateral symmetry: two-sided; has 2 axes of orientation, front to back and top to bottom (crawfish)
KINDS OF SYMMETRY
Asymmetrical
Radial Bilateral
DORSAL
POSTERIOR
VENTRAL
ANTERIOR
CEPHALIZATION
•Most animals with bilateral symmetry have sensory equipment located at the anterior end, including a central nervous system (brain) in the head
•Provides efficient response to stimuli as sense organs encounter stimulus before rest of organism
TISSUE DEVELOPMENT•I
n animals, true tissues are collections of specialized cells isolated from other tissues by membranous layers
•Sponges and a few others lack true tissues
•Gastrulation develops these layers – called germ layers
GERM LAYERS
•Ectoderm: covers surface of embryo; gives rise to outer covering on animal (and sometimes to central nervous system)
•Endoderm: innermost germ layer; lines the pouch that forms during gastrulation; gives rise to lining of digestive tract and organs such as liver or lungs
•Animals that have only these two layers are diploblastic
•Examples: sponges, jellyfish, anemones
TRIPOBLASTIC ANIMALS
•Most animals have a middle germ layer called the mesoderm which fills much of the space between the ectoderm and the endoderm
•Forms muscles and most other organs between digestive tract and outer covering of animal
BODY CAVITIES•M
ost tripoblastic animals have a body cavity – a fluid or air filled space between digestive tract and outer body wall
•This cavity is called a coelom
•A “true” coelom forms from tissues from the mesoderm
•Coelomates – organisms with a true coelom
•Pseudocoelomates – coelom formed from mesoderm and endoderm; also a fully functional body cavity
•Acoelomates – lack a body cavity
PROTOSTOME & DEUTEROSTOME DEVELOPMENT
•Fate of embryonic cells determined very early in development (DETERMINATE)
•SPIRAL cleavage
•Blastopore becomes MOUTH
•INVERTEBRATESexcept ECHINODERMS
•Fate of embryonic cells determined later in development(INDETERMINATE)
•RADIAL cleavage
•Blastopore becomes ANUS
•ALL VERTEBRATES (Fish, amphibians, birds, reptiles, mammals)plus ECHINODERMS
PROTOSTOMESDEUTEROSTOMES
“Exception to the rule”
ECHINODERMS ARETHE ONLY INVERTEBRATEDEUTEROSTOMES