Animal Diversity II Flashcards
What are Deuterostomia?
- Main shared features: » Bilateral symmetry » Triploblastic (ie including mesoderm) » Deuterostome development - Two main phyla (despite appearance, DNA analysis suggests are closely related): » Echinoderms (sea stars, sea urchins) » Chordates (mostly vertebrates)
What are Echinoderms?
- A phyla of Dueterostomia
- echinos = spiky, derma = skin
- Generally slow moving or sessile animals
- Separate male and female individuals
- Appear radially symmetrical, but larvae are bilateral and adults are actually off-centred
- Endoskeleton of hard calcareous plates (ie calcium carbonate)
- Unique water vascular system
How does the Echinoderm water vascular system work?
Water enters through pore, flows into ring canal in centre, then down five radial canals running down entire arm into inflatable tubes
What are some examples of Echinoderms?
- Sea stars
» Arms radiating from central disk
» Everts its stomach into shell of prey, digests it there, then brings it back inside - Brittle stars
» Central disk, long flexible arms - Sea urchin
» Roughly spherical, spines, no arms but 5 rows of tube feet - Sea cucumbers
» Look quite different, but 5 rows of tube feet
What are Chordates
- organisms part of phylum chordata
- All chordates possess 4 features shared at some point during their development
Draw the diagram of a Cordate at the stage where is possess all four shared features
in back of work book
What is the Notochord?
- one of the four features inside a cordate
- Flexible rod
- Sits below nerve cord
- Provides skeletal support
- Replaced by bones in vertebrates (vertebral column)
What is the Dorsal, hollow nerve cord?
- one of the four features inside a cordate
- Develops into spinal cord and brain (ie, central nervous system) in adults
What are the Pharyngeal slits or clefts
- one of the four features inside a cordate
- Used for suspension feeding in invertebrates
- Develop into gills in non-tetrapod vertebrates
» Develop into parts of ears and necks of tetrapods (four limbed vertebrates)
What is the Muscular post-anal tail
- one of the four features inside a cordate
- Extends posterior to anus
- Muscular →movement
- Often greatly reduced during embryonic development
Do all Chordates have vertebrae?
No, there are 2 chordate classes that don’t have vertebrae
What are the 2 hordate classes that dont have vertebrae?
» Cephalochordata (lancelets)
• Filter feeder, up to 6 cm
• Relatively rare, but at high density when found
» Urochordata (tunicates)
• Chordate characteristics apparent in larva
• Settles on substrate, then undergoes radical metamorphosis
• Filter feeder
What are Cyclostomes?
- Split into two main groups:
- Myxini (hagfishes)
» Jawless
» Reduced vertebrae, cartilage skull
» Marine
» Scavengers, teeth made of keratin - Petromyzontida (lampreys)
» Jawless
» Skeleton out of cartilage
» Larvae life in freshwater streams, then migrate into sea as adults
» Most are parasites
What was one of the major steps in evolution that expanded the diet of animals?
The evolution of Jaws
What are Condrichthyes?
- It means (“cartilage fish”)
- Sharks
» Biggest vertebrate predators in oceans
» Some suspension feeders, but most are carnivores → good sensory systems (vision, smell, sounds and electric field) - Rays and skates
» Flat, bottom dwelling, eat molluscs - Chimaeras
» Live in deeper waters
» Feed on shrimps, molluscs, sea urchins
How long ago were Megalodon’s around, on average how big were they and what did they eat?
» Huge 18m long shark
» Lived 16-2.5 MYA
» Predator of large whales
What evolutionary step happened after jaws?
well the calcified boned sort of happened at the same time as lungs started to develop in organisms
What are Osteichthyes?
- Bony fishes
- Bony endoskeleton (calcium phosphate)
- Breathe by passing water over gills (in mouth, through pharynx, out operculum)
- Maintain buoyancy with air-filled sac (swim bladder), which developed from lungs
How many classes of Osteichthyes are there?
3 classes » Ray-finned fishes (Actinopterygii) • Over 27,000 species » Lobe-finned fishes (Sarcopterygii) • 2 species of Actinistia (coelocanths) • 6 species of Dipnoi (lungfishes)
What was the next evolutionary step after lobed fins?
Limbs with digits (fingers and toes)
What are tetrapods?
- (“four limbs”)
- Amphibians, reptiles and mammals
- Appear 365 MYA, after colonisation of land
- Clear evolution of limb from fins in fossil record
How many Orders does class Amphibia have?
- 3 major orders
» Salamanders (order Urodela, “tailed ones”)
» Frogs (order Anura, “tailless ones”)
» Caecilians (order Apoda, “legless ones”)
Why are Apoda classified as tetrapods?
Even though they don’t have legs their ancestors did and due to the lifestyle of these animals they would have lost them somewhere along their evolutionary history.
What happens during the life cycle of a frog?
- Larval stage = tadpole
» Aquatic herbivore
» Initially has gills, tail, no legs - During metamorphosis:
» Lose tail
» Develop legs, eardrums
» Most species lose gills and develop lungs
» Modify digestive system to carnivorous diet - Adult is a terrestrial (land-based) hunter
» Moist skin to improve gas exchange
