Animal Flashcards
3 major steps in evolution of animals
- origins of life (prokaryotes) 4bya
- eukaryotes 2.1 bya
- multi-cellularity 1.5 bya
Modern Choanoflagellates
Closest living relatives of animals
Single celled protists
Gastrula
Multilayer, multi-celled embryonic structure, develops from blastula
Choanocytes
Specialised cells which line porifera, contain flagella which spin to filter nutrients from water
Osculum
Tip of pore in sponge with expels water
Tissue definitions
A group of cells which have a common structure + function and are integrated
Diploblastic
Develops from 2 embryonic tissue layers (endoderm and ectoderm) separated by a non-cellular layer (mesoglea)
Cnidaria key features
Radial symmetry
Diploblastic
Sponges key feature
No true tissues - cells do not coordinate function
Features of animals
- multicellular
- heterotrophs
- no rigid cell layer
- reproduction
- nerve and muscle cells
Two forms of Cnidaria
Medusa or polyp
Clades of cnidaria
Anthozoans, medusozoans
Blastocoel
Hollow area inside the blastula
Triploblastic
3 embryonic cell layers - ectoderm, mesoderm, endoderm
Deuterostomes
- Blastopore becomes anus
- mouth develops later
- Radial 8 cell stage
Protostomes
- Blastopore becomes mouth
- Anus develops later
- Spiral 8 cell stage
Lophotrochozoa
- 18 phyla
- some have lophophore feed apparatus
- some have trochophore larva
- grouped due to molecular evidence
Platyhelminthes
Parasitic and diverse (20,000 species)
No anus - waste diffused across body
Acoelomate
No body cavity
Schistosoma
Infects 200 million worldwide
Worse in tropical areas
Hosts are snails and human - require both for lifecycle
Ecdysozoa
Group of phyla which moult
Key characteristics of arthropods
Segmented body plan
Jointed segmental appendages
Cuticular exoskeleton
Arthropod joints
Muscles located on the inside, connect directly to exoskeleton
Structure of cuticular exoskeleton in arthropods
Epicuticle - protects from water loss
Exocuticle - thickest, protein rich layer that provides structure
Endocuticle - soft flexible layer, cushions body and allows movement
Epidermis - cellular layer
Seta - sensory hairs which run through structure and attach to sensory neurons
Major arthropod groups + body parts
Chelicerates - prosoma + opisthosoma
Myriapods - head + trunk
Crustaceans - head + pereon + pleon
Insects - head, thorax, abdomen
Arachnida characteristics
Mostly terrestrial
Mostly carnivorous
Most have 8 legs
Orders of arachnida
Pseudoscorpions
Opiliones
Acari
Araneae
Chelicera
Mouthparts of subphylum chelicerata
Araneae features
Cephalothorax + abdomen
1 pair chelicera
1 pair pedipalps
Book lungs
Silk glands
Book lung
Spider respiratory system that allows spider to breath simultaneously with lungs and tracheae
Opens to spiracles
Membrane allows fusion of air and blood flow
Spinneret
Organ for silk production
Spigots - pump silk threads out
Spider silk
Made up of proteins - fibroin
Protein glues
Myriapoda features
One pair antenna
Head + trunk
Terrestrial
Permeable epicuticle
Spiracles
Centipedes
One pair of legs per segment
First pair of legs makes forcipules for venom
Venom
Antenna
Flattened body
Millipedes
Herbivores
Two pairs of legs per body segment
Tubular body
Repugnatorial glands
Crustacea features
Head, pereon, pleon
Head has 5x appendages
Biramous appendages
Mostly marine
5x head appendages in crustaceans
2 pairs antennae
Mandible
2 pairs maxillae
Biramous appendages
Branched appendages - protopod branches into exopod and endopod
Hexapoda features
3 segments - head, thorax, abdomen
6x thoracic appendages
Insecta features
Hardened exoskeleton
Coelomate
Haemocoel
Spiracles
Two types of eyes - ocelli and compound
Insecta circulatory systems
Open system
Dorsal blood vessel - exports metabolic waste products
Insect digestive system
Pharynx - grinds food
Crop - digests food
Insect nervous system
Cerebral ganglia
Ventral nerve cord
Hemimetabolous development
Incomplete metamorphosis
Nymphs resemble adults
Gradual change
Homometabolous
Complete metamorphosis
Four stages - Egg, larva, pupa, adult
Cause of large variation in insects
Malaria
Carried by anopheles mosquito
3.3 billion at risk
241 million cases worldwide each year
Why breathe air - relative
Air is less dense and more oxygen rich than water
143L of water needed for 1L O2, compared to 4.8L air
Tiktaalik
Discovered in Canada,
Devonian ~350 mya
Descent with modification - fishbian sequence
Toktaalik fish / tetrapod characteristics
Fish - scales, gills, lungs, fins
Tetrapod - ribs, neck, fin skeleton, flat skull, eyes on top of head
Amphibian characteristics
Bony skeleton - ribs present
Varied body forms
4 limbs
Smooth moist skin
Large mouth
Gills, lungs, skin exchange
3 chambered heart
Seperate sexes
Amphibian orders
Salamander, frogs, caecilians
Amphibian life cycle dependant on water for…?
Reproduction
Respiration
Amphibian life cycles
Egg to tadpole to frog
Thyroxin triggers metamorphosis
Nz primitive amphibians - 7 species
9 pre sacral vertebrae
Amphicoelous vertebrae - indents on both sides
No tympanic membrane or vocal sacs
Froglets from capsule
No webbing
Amniotic egg parts
Embryo, yolk sac, chorion, allantois, albumen, amnion, she’ll
Other amniotic adaptions
Rib breathing, keratinised scales, increased efficiency
Reptilian characteristics
Body with horny epidermal scales
Paired limbs, 5 toes
Ossified skeleton
Lungs not gills
3/4 chambered heart
Ectothermic
Internal fertilisation
Eggs covered with shell
Squamata (snakes)
Loss of legs
Trachea allows breathing while feeding
Unique sensory organs - pit organs, Jacobsons organ
Kinetic skull
Pit organs
Detect infrared via temp stimulation of ion channels
Jacobsons organ
Snakes smell air with tongue
Role of venom
Adjust level of dose, operate by blocking acetylcholine receptors (affect neurotransmitters)
Activates lipase (breakdown cell membranes)
Cause necrosis (pre digests tissue)
Bite and release approach tags prey and release disintegrins
Sphenodonta
Tuatara
2 bony arches on skull
Fused teeth to jaw
No external ear holes
Parietal organ
Salamander breathing
Gas exchange mix of skin and lungs
Lizards breathing
Intercostal muscles, less cutaneous exchange
Tortoise breathing
Carapace interferes with intercostals so movement encourages lung expansion
Crocodiles breathing
Extended respiratory system - breath through naris
Liver opens and closes lungs
Features of living birds
Wings and feathers
High parental care
Externally incubated eggs
Beak but no teeth
large brains
Endothermic
High metabolic rate
Traits for flight in birds
Honeycombed bones
Feathers shaped into aerodynamic wing
Superior power output - metabolic systems
Flight capacity
Bird bones
Pneumatic (air filled)
Appear slender but higher density
Redistribution of mass
Key structural features for flight
Rigidity
Reduction
Redistribution
Limb modification for flight
Primary feathers
Flight feathers
Rigidity adaptions for flight birds
Thoracic and cervical vertebrae bound together
Large keeled sternum (flight muscle attachment)
Uncinate processes (lateral bracing, strengthens rib cage)
Pelvis fusion (string attachment for legs- ilium, ischium, pubis, vertebrae)
Reduction adaptations for flight
Lack urinary bladder
No teeth - mastication via gizzard
Gonads small
One ovary
Size
ZPA
Zone of polarising activity
Fgf8 and function
Fibroblast growth factor 8 causes extension of wings in embryo
Pelagornithid
Ancient bird with 21 ft wingspan
Air sacs in birds
Fill and store air
Allow unidirectional air flow through lungs
Metabolic rate increases 15x during flight
Bar headed geese adaptations
High breathing rates
More mitochondria and blood flow in muscles
Haemoglobin has higher oxygen capacity
Higher heart rate at altitude
Frigate bird
Uses air flow of tropics to stay in air
Advantages of a coelom
Support - hydrostatic skeleton
Protection of organs
Nutrient transport
Waste removal
Reproduction
Mantle function in molluscs
Secretes shell, encloses gill
Radula
Hardened structures which resemble teeth
Mollusc body systems
Protostomes
Osmoregulation
Open circulation
Nephridia (kidney like waste excretion)
Gastropoda torsion
90-180 degree twisting during larva development
Torsion advantage is clean water enters from direction of travel
