Unit 12 Terms - Chordata Flashcards
Five KEY characteristics of chordates
- notocord
- dorsal tubular nerve cord
- pharyngeal pouches or slits
- endostyle or thyroid gland
- postanal tail
Five KEY characteristics of chordates
- notochord
- dorsal tubular nerve cord
- pharyngeal pouches or slits
- endostyle or thyroid gland
- postanal tail
Notochord
- means back cord
- rodlike, simirigid hydrostatic organ
- stiffens the body, provides internal support
Dorsal tubular nerve cord
- dorsal to the digestive tract, hollow, only one
- back side of the body
Pharyngeal pouches or slits
- may form gills or other structures
- always occur, but may only be during one part of development
- do not always function for respiration
Endostyle or thyroid gland
- both located under the pharnyx
- both have cells that produce a hormone
- endostyle: produces mucus
- thyroid gland: does not produce mucus
Postanal tail
- tail that extends beyond the anus, muscular tail
- always occurs, but may only be during one part of development
Subphylum Urochordata
- means tail-chordates, commonly called tunicates
- 3,000 species
- sessile
- has a usually touch non living tunic
Subphylum Cephalochordata
- means head-chord, commonly called lancelets or amphioxus (both ends, sharp)
- 32 species
Heterocercal tail
two parts, not even
Different types of scales
- placoid
- ganoid
- cycloid
- ctenoid
Compare and contrast hagfishes and lampreys
- unique to hagfish:
*make a lot of slime, literally impossible to hold onto
(defense mechanism)
*scavengers (find dead animals and will feed)
*latch with mouth and with make a knot and use it to tear
food off
*only marine
*no larval stages - unique to lamreys:
- parasitic as adults
- some adults do not feed, will reproduce and die
- freshwater and marine, some may go back and forth
- external fertilization
- have a dorsal fin
Characteristics of chondrichthyes
- about 1,000 species
- named for their chonologanis skeleton
- if they have scales, they are placoid scales
- when we look at their codal fin, they have a heterocircle tail
- internal fertilization
Characteristics of Actinopterygii
- ray finned fishes
- largest group of any chordate
- 31,000 species, but more species are found every year
- most are homocercal, but some are heterocercal
- fins are supported by bony rays
- bony skeleton
- either have oviparous or viviparous
- have a swim bladder, used for buoyancy, some use it as a lung
- operculum
- one circuit of blood circulation
Characteristics of Sarcopterygii
- lobe finned fishes
- part of their fins are muscular
- two circuits of blood circulation
- example: lung fish
- ## have a swim bladder
Placoid scales
small, hooked like structure, almost tooth-like, spaced out
Ganoid scales
diamond shaped, very thick and bony
Cycloid scales
circular pattern, smooth margin, overlap neighboring scales
Musculoskeletal Modifications
- notochord
- centrum of vertebra
- neural spine
Physiology
- pharyngeal slits
- dorsal aorta
- muscularized gut
- chambered heart
- ventral aorta
- aortic arches
Head, brain, and sensory systems
- olfactory bulb
- brain
- eye
- otic vesicle
- neural arch
- spinal cord
