Basic Chordate Information Flashcards
(27 cards)
What is Chordata?
a phylum that contains deuterostome animals that possess 5 specific characteristics (dorsal, hollow nerve cord, notochord, pharyngeal slits/perforated pharynx, post-anal, muscular tail, endostyle/thyroid) during at least one stage in their life cycle
What are the 5 major characteristics of Chordates?
- Notochord
- Hollow, dorsal nerve cord
- Pharyngeal gill slits / perforated pharynx
- Muscular, post-anal tail
- Endostyle or thyroid
What phyla are Chordates most closely related to?
Hemichordata and Echinodermata
What are the 11 classes of Chordata?
- Lancelets
- Tunicates
- Hagfishes
- Lamprey
- Cartilaginous fishes
- ray-finned fishes
- Coelocanths
- Lungfishes
- Amphibians
- Reptiles
- Mammals
T or F: all of the animals in Chordata are vertebrates
FALSE. There are 2 invertebrate groups
What are the 2 invertebrate groups of Chordates?
Lancelets and tunicates
What are the vertebrate groups of chordates?
hagfishes
lampreys
cartilaginous fishes
ray-finned fishes
lungfishes
amphibians
reptiles
mammals
Describe pharyngeal gill slits/perforated pharynx
slits or holes in the pharynx (posterior to mouth) that allow water taken in from the mouth to leave the body without moving through the digestive tract first
What is the purpose of pharyngeal gill slits/perforated pharynx in invertebrate chordates?
used for suspension-feeding
What have the pharyngeal gill slits/perforated pharynx been modified for in other chordates?
gas exchange in aquatic vertebrates
jaw support
hearing
What is the notochord?
the skeletal structure (elastic rod) between the digestive tube and the nerve cord that flexes laterally
What is the notochord made of?
large, fluid-filled cells coated in stiff, fibrous tissue
At what life stage(s) is the notochord present in most vertebrates?
embryo
Does the notochord persist into adult phases?
No, but remnants of it are present in adults (ex. disks between vertebrae)
What is the hollow, dorsal nerve cord?
a tube that is dorsal to the notochord which develops from the ectoderm
What does the hollow, dorsal nerve cord develop into?
the brain and spinal cord
What composes the muscular, post-anal tail ?
muscular and skeletal components
What is the purpose of the muscular, post-anal tail in aquatic species?
propulsion force
What is the endostyle?
a groove-like glandular structure on the floor of the pharynx
produces mucus to trap food particles
What are the purposes of the endostyle?
to produce mucus to trap food particles
iodine metabolism
What can the endostyle develop into in more recently derived chordates? give an example
a thyroid gland
ex. larval lamprey have an endostyle and adult lamprey have a thyroid
What is possibly the earliest known chordate?
Pikaia
When was Pikaia discovered?
in 1911 in the Burgess Shale by Charles Doolittle Walcott
When did Pikaia likely appear?
During the Cambrian period
