Chordates Flashcards
what are the 5 characteristics of chordates
- notochord
- dorsal hollow nerve chord
- pharyngeal slits
- endostyle for filter feeding
- postanal tail for propulsion
notochord
- becomes the vertebral column in Gnathostomata
- persists in jawless vertebrates and protochordates
- organizational role in development of nervous system
dorsal hollow nerve chord
-dorsal to the digestive tract
Note: invertebrates have a nerve chord, but it is ventral and solid
endostyle or thyroid
endostyle is present in protochordates and lamprey larvae. It secretes mucus that traps food particles brought to the pharyngeal cavity.
Thyroid gland regulates metabolism and hormones
protochordata
do not have a true brain, skull, vertebral column
craniata
have a skull, vertebral column
vertebrata
Gnathostomata
craniates with jaws
placoid scales
- Small, conical, toothlike structures
- Typical of chondrichthyes
- Modified to teeth in sharks
Ganoid scales
- Diamond shaped
* Early bony fishes and living gars
Cycloid and Ctenoid scales
- Arranged in overlapping rows
* Typical of teleost fish
Chondrychthes
- No swim bladder (use tail to provide upward lift)
- Heterocercal tail: assymetrical, provides lift
- cartiligenous
osmotic regulation of freshwater fish? marine fish?
freshwater: hyperosmotic regulators
marine: hypoosmotic regulators
hyperosmotic regulators
- greater concentration of salt in the fish
- water only enters through membranes (gills)
- diluted urine
- kidneys push water out of the fish
- salt-absorbing cells in the gill move salt from the water to the fish
hypoosmotic regulators
- contain a small amount of salt than the surrounding water
- salt-secretory cells in the gill move salt out of the body
- salt is voided in feces or excreted by the kidney
How do gills work?
idk
Myxini
- Jawless
- Entirely marine group
- Feed on annelids, molluscs, crustaceans, and dead or dying fishes
- Scavengers and predators (not parasitic)
- Poorly developed eyes
- Keenly developed sense of smell and touch
- Produce slime as a defense mechanism
- Can tie itself into a knot
- Has a rasping organ (keratinized scales on tongue)
rasping organ?
snail, Myxini, Petromyzontida (so Agnatha)
Petromyzontida
- They use tooth-like plates of keratin for rasping a hole, through which fluids and tissues are sucked.
- half are parasitic
Actinopterygii
Symmetrical homocercal tail allows for greater speed
- swim bladder
- gills
Sarcopterygii
Diphycercal tails
lungs and gills
Urochordata
- tunicates
- Only the larval form bears all the chordate hallmarks
- solitary or colonial
- Most sessile as adults, some free-living
Cephalochordata
- Lancelets
- Originally bore the generic name Amphioxus
- Amphioxus: Greek, amphi, both ends + oxys, sharp
- Modern survivors of an ancient chordate lineage
- Slender, laterally compressed, translucent animals
- Inhabit sandy sediments of coastal waters
- 5 distinct characteristics of chordates but in simple form
- Lack features found in true vertebrates • No brain
what are the adaptations of amniotes
- Amniotic egg
- Thicker and more waterproof skin
- Rib ventilation of the lungs
- Stronger jaws
- High-pressure cardiovascular systems
- Water-conserving nitrogen excretion
- Expanded brain and sensory organs
