Lab 7 Flashcards
4 characteristics of Chordates
Notochord
Dorsal, hollow nerve chord
Pharyngeal slits
Muscular, post anal tail
Notochord
flexible rod, located between digestive tube and nerve chord that provides support along the length of the animal
Dorsal, hollow nerve chord
a bundle of nerve cells that runs the length of the body. All other animals have solid nerve chords and they are usually ventral
Pharyngeal slits
slits in the pharynx that opens to the outside of the animal, allowing water to enter the mouth and leave the body without passing through the entire digestive tract
Muscular, post anal tail
initially evolved for locomotion in water
Cephalochordata
(lancelets) resemble the ideal chordate, have all 4 characteristics, as larvae they are free swimming and filter feed on plankton suspended in the water. As adults they bury themselves in sand and filter feed by drawing water through their pharyngeal gill slits.
Urochordata
(Tunicates) resemble chordates in their larval stage where 4 traits are found. As adults they are sessile and use pharyngeal slits for suspension feeding. Adults are characterised by their 2 siphons. One siphon draws water into the organism, from which food is collected in a mucous net and the other expels the filtered water. This can be done quite rapidly, giving the tunicates their more common name of sea squirts
Myxinoidea
(hagfishes) first to posses neural crest and skull, so they belong to caraniates. Skull is of cartilage, but now jaw or backbone, technically a invertebrate. Live at bottom of ocean, live as deposit feeders, scavenging worms and sick or dead fish.
Lampreys
Oldest living lineage of vertebrate chordates. Have skull and backbone but no jaws. Most are parasitic, feed by sucking on prey and using rasping tongue to break the skin and digest blood.
Notochord and post anal tail innovation
Provides support and propulsion for underwater movement
Pharyngeal slits innovation
allows suspension feeding and gas exchange
Cephalisation innovation
the is toward increased cephalisation and development of a larger brain allowing better sensory perception and reaction to the surrounding environment
Jaws innovation
increases food diversity
Mineralised and joint skeleton innovation
more flexibility , protection and support
Lungs
breathing on land
Limbs
walking on land
Heart chambers
2 – 3 – 4 increased heart complexity allows improved circulation and separation of oxygenated and deoxygenated blood.
Amniotic egg
reproduction without water
Heart
a. 2 chambered: fish
b. 3 chambered: amphibians and reptiles
c. 4 chambered: birds and mammals
3 over 2
has double circulation, 2 has single
4 over 3
4 has separated oxygenated and deoxygenated blood
Double verses Single
Double circulation in faster than single and it flows through the lungs, in single in flows through the capillaries and it is much slower
Gnathostomes
Jaw and mineralised skeleton
Osteichthyans
Lungs and lung derivatives
Terapods
legs
Amniotes
Amniotic eggs
Amphibians
limbs, lungs, jaws, vertebral column, cranium, eggs in water, feed on land, gas exchange. Still tied to aquatic because they lay eggs in water, skin needs to stay moist and gas exchange.
Amniotic eggs
The amniotic egg is composed of 4 membranes, including a yolk that provides nutrients to the developing embryo. Most amniotic eggs have a shell; however, in mammals, the shell has been lost and the embryo develops within the amnion within the mother instead. Significantly reduce hydration of egg in air. Allows amniotes to occupy wider range of habitats
Reptiles on land
limbs for walking, breath on land
Reptiles and Birds
Share: Jaws, vertebral column, limbs, amniotic egg, cranium, eyeballs
Birds: Eggs shell calcaneous and hard, wings, feathers, porous skeleton easier for flight
