Wk1-2 Flashcards
What is an animal?
Animas are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers
What are the main characteristics of an animal?
Nutritional mode
Cell structure & specialisation
Reproduction and development
What is a vertebrate?
Animals that belong to the Phylum Chordata that have vertebral column (also called backbone) and specialized sensory organs are considered vertebrates
Phylum Chordata
1) A dorsal, hollow nerve cord
2) A notochord – a flexible, longitudinal rod located between the digestive tract and the nerve cord
3) Pharyngeal slits – gill structures in the pharynx, the region of the digestive tube just behind the mouth
4) A post-anal tail – a tail to the rear of the anus
3 categories of terrestrial foragers
Arboreal (in trees)
Aerial
Fossorial (underground)
Name a benefit of classification of organisms with unique binomial name and genus species?
Aids to explain evolutionary relationships
Phylogeny shows
A groups evolutionary history
Are all chordates vertebrates?
No
During which period of evolution did the first mammals and birds appear in Australia?
Cretaceous period
In the rest of the world it appeared during the Triassic period
- Australia is different has it has been isolated for a very long time (continental drift)
What are the two main groups of vertebrates distinguished by innovation in embryonic development?
Amniotes and Non-Amniotes
The division between non-amniotes and amniotes corresponds roughly to aquatic and terrestrial vertebrates, although few fish and amphibians lay non-amniotic eggs in nest on land
Amniotes
Characterised by the existence of a structure during embryonic development that consists of 3 membranes that are able to provide protection, nutrition and exchange of oxygen to the embryo itself. These 3 membranes come form the inside of the embryo and are a huge evolutionary improvement.
Amniotic egg
Chorion: With the allantois membrane, exchange of gases between the embryo and the air
Amnion: Protects the embryo in a fluid-filled cavity that cushions against mechanical shock
Allantois: Disposal of metabolic wastes
Main obstacles from water to land
- Egg desiccation
Solution: Amniotic egg (waterproof eggshell that prevents eggs from drying out before they’ve hatched) - Respiration
Solution: Gas exchange was transferred from gills to lungs that evolved from the swimmer bladder - Gravity (different density)
Solution: Limbs evolved from fins. Vertebrates were modified to transmit their body weight through the limbs to the ground
Hagfish
No skeleton
No notochord in adults
Brief order of evolution (most primitive vertebrates - most evolved)
Hagfish
Lamprey
Cartilaginous fishes/Bony fishes
Amphibians
Reptiles
Birds
Mammals
Lampreys
Early version of a vertebral column
Cartilaginous fishes/ Bony fishes
Powerful jaws (sharks and fishes)
Bony skeleton reinforced by calcium and flexible cartilaginous skeleton
Lateral line (system of sense organs that are able to detect movement and changes in pressure in the surrounding water, help them to judge their environment and catch prey)
Swim bladder (helps fish to stay buoyant in water)
Amphibians
Tetrapod’s (four-limbed vertebrates)
Deposit eggs in the water
Aquatic larvae
Moist skin
Reptiles
Ectotherms (absorb heat from outside)
Waterproof skin covered by scales
Breathe through their lungs
Amniotic eggs
Birds
Endotherms (derives heat from own metabolism)
Light skeleton with bones
Specialised air sacks for flight
Gizzard to grind food, no teeth
Feathers made of keratin providing insulation and enable flight
Mammals
Various embryo development. Most embryos develop in uterus
Hair and subcutaneous fat (to help retain metabolic heat)
Mammary glands (produce milk rich in macronutrients and vitamins)
Differentiation of teeth (for efficient foraging)
Animals are categorised according to….
General features of morphology and developement
Tissues are
Groups of specialised cells with similar origin and a similar specific function
1st branch of phylogeny distinguishes…
Sponges form all other animals based on structural complexity
- Lack true tissues
2nd branch of phylogeny divides animals based on…
Body symmetry
Radial vs Bilateral
3rd branch of phylogeny division is divides animals based on
Embryonic tissues
Animal embryos have germ layers of embryonic tissues
Germ layers are a group of cells in an embryo that interact with each as the embryo develops and contribute to the development of tissues and organs
Diploblastic: Animals that have 2 germ layers
Triploblastic: Animals that have 3 germ layers: ectoderm, endoderm and mesoderm – A body cavity may be present or absent (can originate a body cavity)
Triploblastic animals can be divided into
Acoelomates: No body cavity
Pseudocoelomates: Body cavity from blastocoel (false body cavity – body cavity filled with liquid)
Coelomate: true body cavity derived from mesoderm, allows organs to be organised. They are attached and can move freely but stops organs from piling on top of each other (chordates are coelomates)
Triploblastic animals
Animals that have 3 germ layers: ectoderm, endoderm and mesoderm – A body cavity may be present or absent (can originate a body cavity)
Diploblastic animals
Animals that only have 2 germ layers
Protostome
molluscs and annelids
Cleavage at 8 cell stage is spiral and determinate
Solid masses of mesoderm split and form coelom
Mouth develops from blastopore
Deuterostome
Echinoderms and chordates
Cleavage at eight cell stage is Radial and indeterminate
Folds of archenteron form coelom
Anus develops from blastopore
Summary Chordates - division branches 1-3
1st branch = have tissues
2nd branch = have bilateral symmetry
3rd branch – are triploblastic deuterostomes
Evolution of 1st vertebrates - Gnathostomes (jawed mouth)
Food filters are modified to form gills (new feeding strategies e.g. biting, tearing)
1st gill arch becomes upper and lower jaws (new food sources e.g. herbivores, carnivores)
2nd gill arch moves forward to clamp the jaws (improved gill ventilation)
Evolution of muscles and fins
Lampreys: Myomeres W-shaped
Amphioxus: Myomeres V-shaped
Sharks and bony fish: Myomeres more complexly folded + fins
- Advantage in controlling 3D environments
- Enhances the development of active pursuit strategies in predatory fish
Circulatory system in fish
Single circuit
The heart is a tube with 2 chambers: 1 atrium and 1 ventricle
The evolution of gills resulted in a low systemic circulation
Circulatory system in amphibians
Double circuit
The heart has 3 chambers: 2 atriums and 1 ventricle (no septum)
The evolution of lungs resulted in a pulmocutaneous and a systemic circuit
Circulatory system in reptiles
Double circuit
Pulmonary and systemic circulation
The heart is a tube with 3 chambers: there is only one ventricle that allows some blood mixing (incomplete septum)
Two arteries that lead to the systemic circuits
Crocodiles have 4 chambers (like birds and mammals)
Circulatory system in mammals
Double circuit: the left ventricle receives and pumps oxygen rich blood while the right side handles only oxygen poor blood. NO BLOOD MIXING
Efficient gas transport essential for movement and endothermy (the organism regulates its own body temperature)
Gas Exchange
is the delivery of O2 and removal of CO2
Respiration
Is the metabolic process that occurs in the cells and produces ATP
Breathing
is the ventilation process that enables us to inhale O2 and exhale CO2
Respiration in amphibians
Inspiration - bucal cavity expands, air is drawn into buccal cavity from outside and into lungs
Expiration - Bucal cavity contracts, air is forced out of nostrils, air is forced into lungs (some mixing)
What lead to cephalisation of the brain?
Bilateral symmetry
Forebrain
Receives and integrates sensory information from nose, eyes and ears
Midbrain
Coordinates reflex responses to sight and sound
Hindbrain
coordinates the reflex control of blood circulation, respiration and sensory input
