1. Chondrichthyes
1.1. Ex: sharks, rays, skates
1.2. Subclass has some species of ratfish and chimaeras
1.3. Skeleton primarily made of cartilage
1.4. Some suspension feeders, but mostly carnivores
1.5. Have short digestive tract with ridge called spiral valve to increase digestive surface area
1.6. Has acute senses of smell, sight, and can detect electrical fields
1.7. Eggs fertilized internally, but can develop in 3 different ways
1.7.1. Oviparous: eggs hatch outside mother's body
1.7.2. Ovoviviparous: embryo develops within uterus nourished by egg yolk
1.7.3. Viviparous: embryo develops within uterus nourished by yolk sac placenta from mother's blood
1.8. Reproductive tract, excretory system, and digestive trace empty into cloaca
2. Enchinodermata
2.1. Ex: starfish
2.2. Slow-moving or sessile
2.3. Thin epidermis covers hard calcareous plates
2.4. Has unique water vascular system
2.4.1. Network of hydraulic canals branching into tube feet functioning in locomotion and feeding
2.5. Sexual reproduction is external
2.6. Most have radial symmetry in multiples of 5 (penta-symmetry)
2.7. Larva have bilateral symmetry
2.8. Divided into five clades:
2.8.1. Asteroidea: sea stars & sea daisies
2.8.1.1. Sea stars:
2.8.1.1.1. Multiple arms radiate from central disk
2.8.1.1.2. Arms grip with tube feet that have adhesive chemicals
2.8.1.1.3. Eat bivalves by prying them open with tube feet and digesting them externally
2.8.1.1.4. Can regrow lost arms
2.8.1.2. Sea daisies
2.8.1.2.1. Armless
2.8.1.2.2. Only 3 know species
2.8.1.2.3. Live on submerged wood absorbing nutrients through membrane surrounding body
2.8.2. Ophiuroidea: brittle stars
2.8.2.1. Distinct central disk
2.8.2.2. Long, flexible arms
2.8.2.3. Some are suspension feeders, others are predators or scavengers
2.8.3. Echinoidea: sea urchins & sand dollars
2.8.3.1. No arms but 5 rows of rube feet
2.8.3.2. Spines used for locomotion and protection
2.8.3.3. Sea urchins eat seaweed using "jaws" on underside
2.8.4. Crinoidea: sea lilies & feather stars
2.8.4.1. Sea lilies:
2.8.4.1.1. Live attached to substrate by stalk
2.8.4.2. Feather stars:
2.8.4.2.1. Crawl using long, flexible arms
2.8.4.3. Both are suspension feeders
2.8.4.4. Changed little through evolution
2.8.5. Holothuroidea: sea cucumbers
2.8.5.1. Lack spines
2.8.5.2. Reduced endoskeleton
2.8.5.3. Dissimilar looks to other enchinoderms
2.8.5.4. 5 rows of tube feet, some used as feeding tentacles
3. Chordates
3.1. All have notochord and dorsal, hollow nerve cord, pharyngeal slits or clefts, and post-anal tail
3.1.1. Notochord: longitudinal, flexible rod between digestive tube and nerve cord. Provides skeletal support
3.1.2. Dorsal nerve cord: develops into brain and spinal cord
3.1.3. Pharyngeal clefts: develop into slits opening outside of body. Suspension-feeding structures in invertebrates, gas exchange in vertebrates (except tetrapods, they develop parts of ear, head, and neck)
3.1.4. Post-anal tail: Often reduced during embryonic development
3.1.5. Contains skeletal elements and muscles
3.1.6. Provides propelling force in many aquatic species
3.2. Some lose these traits past embryonic development
3.3. This phylum contains two basal groups of invertebrates as well as below categories
3.4. Are bilaterally symmetrical coelomates
3.5. Segmented bodies
3.6. Genes associated with heart and thyroid are common to all chordates
3.7. Genes associated with transmission of nerve impulses are unique to vertebrates
4. Vertebrates
4.1. Chordates that have a backbone
4.2. Skeletal system and complex nervous system allow vertebrates to be better at capturing food and evading predators
4.3. Have 2+ sets of Hox genes (lancelets/tunicates have only 1)
4.4. Have vertebrae enclosing a spinal cord, an elaborate skull, and fin rays (in aquatic forms)
5. Reptilia
5.1. Ex: tuataras, lizards, snakes, turtles, crocodilians, and birds
5.2. Have scales to make waterproof barrier
5.3. Most ectothermic: internal termperature mostly regulated via external sources
5.4. Birds are endothermic: capable of independant internal termperature regulation
5.5. Turtles:
5.5.1. All have boxlike shell of upper and lower shields fused to vertebrae, clavicles, and ribs
5.6. Diapsids:
5.6.1. Archosaurs:
5.6.1.1. Crocodilians: belong to lineage dating back to late triassic
5.6.1.2. Birds: nearly every part of body adapted for flight: wings with keratin feathers, lack of urinary bladder, females have 1 ovary, small gonads, and no teeth
5.6.1.2.1. Belong to clade neornithes
5.6.1.2.2. Several groups of birds are flightless:
5.6.2. Lepidosaurs:
5.6.2.1. Tuataras: one surviving species: lizard-like reptiles called tuataras, along with one surviving lineage
5.6.2.2. Squamates: major living lineage which includes lizards and snakes
5.6.2.2.1. Snakes: have chemical sensors, heat-detecting organs, venom, loosely articulated jawbones, and elastic skin
5.6.2.2.2. Lizards:
6. Mammalia
6.1. Amniotes that have: mammary glnds tht produce milk, hair, high metabolic rate due to endothermy, larger proportional brain size to other vertebrates, differentiated teeth
6.2. Are synapsids
6.3. By early cretaceous, 3 living lineages appeared
6.3.1. Monotremes:
6.3.1.1. Ex: echidnas, platypus
6.3.1.2. Egg laying mammals
6.3.2. Marsupials:
6.3.2.1. Ex: opossums, kangaroos, koalas
6.3.2.2. Embryo develops within placenta in mother's uterus
6.3.2.3. Completes development while nursing in maternal pouch called marsupium
6.3.3. Eutherians:
6.3.3.1. Have more complex planceta than marsupials
6.3.3.2. Completes development within uterus, joined to mother by placenta
6.4. Primates:
6.4.1. Ex: lemurs, tarsiers, monkeys, apes, humans
6.4.2. Traits: large brain, short jaws, hands/feet adapted to grasping, short nails, complex social behavior and parental care, forward-facing eyes close together on face, and fully opposable thumb
6.4.3. Three main groups:
6.4.3.1. Lemurs, lorises, and bush babies
6.4.3.2. Tarsiers
6.4.3.3. Anthropoids (monkeys and apes)
6.4.3.3.1. New world monkeys
6.4.3.3.2. Old world monkeys
6.4.3.3.3. Apes: diverged rom old world monkeys about 25-30 mya
7. Tetrapods
7.1. Adaptations include 4 limbs, feet with toes, neck (for separate head movement), fusion of pelvic girdle to backbone, absence of gills, and ears
7.2. Tiktaalik, nicknamed fishapod, was a fish/tetrapod hybrid
7.3. First tetrapods appeared 365 million years ago
8. Actinastia
8.1. Ex: coelacanth
9. Actinopterygii (ray fins)
9.1. Ex: yellowfin tuna
9.2. Fins modifed for maneuvering, defense, and other stuff
10. Gnathostomes
10.1. Vertebrates with jaws
10.2. Have hinged jaw used to grip food firmly
10.3. Jaws hypothesized to have developed from skeletal rods supporting gill slits
10.4. Have genome duplication (inlcuding Hox gene duplication), enlarged forebrain giving better smell and vision, and lateral line system (detects vibrations)
11. Ostelchthyans
11.1. Nearly all have bony endoskeleton
11.2. Aquatic osteicthyans are what we call fish
11.3. Have lateral line system
11.4. Most oviparous, some have internal fertilization and birthing
11.5. Breathe by drawing water over gills protected by operculum
11.6. Control buoyancy with air sac called swim bladder
12. Lobe-fins
12.1. Muscular pelvic and pectoral fins used to swim and "walk"
12.2. Three lineages survive: coelacanths, lungfishes, and tetrapods
13. Amniotes
13.1. Amniotic egg was key adaptation to life on land
13.2. Most amniotic eggs have shells
13.3. Other adaptations include impermeable skin and rib cage ventilates lungs
14. Cyclostomes
14.1. Myxini (hagfish)
14.1.1. Have cartilaginous skull
14.1.2. Have reduced vertebrae
14.1.3. Have flexible rod of cartilage derived from notochord
14.1.4. Have small brain, eyes, ears, and "teeth"
14.1.5. Marine, most are bottom-dwelling scavengers
14.2. Petromydontida (lampreys)
14.2.1. Parasites that eat by clamping mouth to live fish
14.2.2. Inhabit marine and freshwater spots
14.2.3. Have cartilaginous segments surrounding notochord
14.3. Lack backbone, but have rudimentary vertebrae
14.4. Only 2 remaining lineages of jawless vertebrates
15. Dipnoi
15.1. Ex: lungfish
15.2. Gills main organs for gas exchange, but also surface to gulp air
15.3. 1/3 surviving lobe-fins are tetrapods, a group that adapted to land
16. Amphibia
16.1. Contains 3 clades:
16.1.1. Urodela: salamanders
16.1.1.1. Amphibians with tails
16.1.1.2. Paedomorphosis is common in aquatic species
16.1.1.2.1. Paedomorphosis: retention of juvenile features in sexually mature organisms
16.1.2. Anura: frogs
16.1.2.1. Powerful hinds legs
16.1.2.2. Frogs with leathery skin are called toads
16.1.3. Apoda: caecilians
16.1.3.1. Legless, nearly blind, and resemble earthworms
16.1.4. Amphibian means "both ways of life"
16.1.5. Most have moist skin to help lungs with gas exchange
16.1.6. Fertilization external in most species, and eggs require moist environment
16.1.7. Some have males or females carry eggs on back, in mouth, or in stomach
17. Cephalochordata
17.1. Ex: lancelets
17.1.1. Named for bladelike shape
17.1.2. Marine suspension feeders
17.1.3. Retain characteristics of chordate body plan as adults
18. Urochordata
18.1. Ex: tunicates
18.1.1. Resemble chordates during larval stage
18.1.2. Draw in water through incurrent siphon, filtering food particles
18.1.3. Highly derived & have less Hox genes than other vertebrates