What is Phylum Chordata
four characteristics of phylum Chordata
- 1. dorsal hollow nerve cord..(forms brain)
- 2. post anal tail
- 3. notochord (stiff flexible rod extending the length of body
- 4. pharyngeal gill slits ( located in pharynx may form resiratory organs)
Are humans in phylum Chordata?
Yes, but only retained characterist we have past the embryonic stage of life is the Dorsal Nerve Cord
1st group in phylum Chodata is the...
The invertebrates make up of what two subgroups
- 1. Celphalchordates: Lancelets
- 2. Urochordates: Sea squirt, tunactes
- retain all 4 chordate features as adults
- They live nearly barried in sand
- Have cilia which draws food into mouth
Urochordates ( Tunicates)...
- Sea squirts:
- exhibit all key chordate features
- filter feeders as adult and lost tail and notochord
- have encircling band of muscles which propels them forward
include all chordates that have a skull and encloses a brain...Hagfish
what is significant about the craniates development
First ones to start having a backbone..Vertebral colum composed of bone or cartilage (more flexible than bone)
Tunicates and sea squits are both Urochordates which are different from lancelets or Celphalchorates by...
only having notocord as larva and not having jaws but having actual backbone
two subgroups of Carniates:
Next Subgroup of Chordates are Chondrichthyes..
include Sharks, skates, rays
they have cartilaginous skeleton, and leathery skin with tiny scales
Cartilaginous are predators and...
two chambered hearts, internal fertilization, Sinks when not swimming b/c lack a swim bladder
What is a swim bladder
something that helps fish stablize in water so they do not sink
Boney fish (osteichthyets) include
most fish in the ocean from sea horse to angler fish
Boney fish have 2 subgroups
- 1. ray finned: angler fish, moray eel, seahorse
- 2. lobe finned fish: lung fish and coelacanth
Ray finned fish are most diverse and abundant of vertebrates:
structure of fins (webed with body spines), boney skeleton, interlocking scales, 2 chamber hearts, gills for respiration, swim bladder, human food source greatly impacts their population
lobed finned fish:
- ones that live in mud: lungfish. Live in freshwater habitats, low oxygen, gills and lungs..
- also they evolved to reptiles amphibians and mamals today,
Next subgroup in Chordates: Amphibians
frogs toads, salamanders, caecilians
Need aquatic enviorment expecially when young. Lungs do not fully develope until adults. 3 chambered heart, moist skin, 4 limbs!!!!, sexually reproduce using external fertilization
limbless, and look like very large earthworm
Next subgroup in Chordates: Reptiles:
Lizards, snakes, alligator, crocodiles, turtles, birds
lungs, Adapted to life on land..a step up from amphibians. tougher scally skin protects against loss of water. internal fertilization..Amniotic egg..amnion (fluid filled membrane prevents drying out. 3/4 chamberd hearts more efficant then amphibian chambed heart by seperating oxygen/deoxygenated, do not breath through skin, Skeleton: better movement
Snakes are unusual..
special sensing organs track prey w temp. can have Venom, jaw joints!!
move babies from eggs to water in mouth
leatherback eats jellyfish
- appear in fossil record 150 million years ago..
- Feathers!! scales on legs. Earliest know bird Archaeopteryx
Birds: how do they adapt for flight
- 1. feathers
- 2. hollow bones
- 3. reproductive organs shrink when not matting periods
- female, single ovary
- 4. nervous system provides extraordinary coordination and balance for flight, acute eyesight
Birds are Warm blooded and health/breathing
- and 4 chambered heart
- Air sacs that provide a continuous supply of oxygenated air to the lungs, and even when bird exhales
The final subgroup of chordates: Mammals!!
250 million years ago: Mammary glands, warmblooded, 4 chambered heart, hair that protects and insulates, legs desighned for running rather than crawling, sweat scent, sebaceous (oil producing glands)...not found in other vertebrates
Three types of Mammals:
- 1. Monotremes: egg laying (leathery eggs) mammals, Platypus, echidnas.
- 2: marsupials:SACS
- 3. Placental mammals: highly diverse!! rodents 40% of mammal species. 20% are bats