Vertebrates Flashcards
What are the general characteristics of the phylum Chordates?
- Bilateral symmetry/triploblastic
- Coelomate
- Deuterostomes (anus first then mouth)
- complete digestive tract
- closed circulatory system
- most have endoskeleton
- Two groups of invertebrates, rest are vertebrates
What are the DEFINING characteristics of the phylum Chordata?
- notochord
- dorsal, hollow nerve cord
- pharyngeal slits or clefts
- post-anal tail
Humans are chordates, but they lack the defining characteristics of chordates because they were developed into something else, tell me what each of the 4 characteristics of chordates developed into in humans.
- Notochord was replaced by vertebrae
- Nerve cord developed into spinal cord
- pharyngeal slits formed eustachian tubes
- postanal tail is present as embryo but regresses
What are vertebrates?
Chordates with a backbone
What are gnathostomes?
Vertebrates with jaws (think gnom gnom gnom)
What are tetrapods?
Gnathostomes that have 4 limbs
What are amniotes?
Tetrapods that have terestrially adapted egg
What are mammals?
amniotes that have hair and produce milk
What are humans?
Mammals that have a large brain and bipedal locomotion.
Describe a lancelet (invertebrate)
Chordate
Named because of bladelike shape
Marine suspension feeder
Describe a Tunicate (invertebrate)
Chordate
closer related to chordates than lancelets
resemble chordates during larval stage, but lose characteristics in adulthood
Have incurrent and excurrent siphon that filter food in water
What are the defining characteristics of a vertebrate?
- Vertebral column replaces embryonic notocord
- Skull protects brain, high degree of cephalization
- Endoskeleton used for protection and muscle attachment
- Large coelom and internal organs, various body systems
Describe an agnathan (clade: cyclostoma).
Vertebrate
Jawless fish
cartilagenous skeleton
no scales or paired fins
What are two examples of an agnathan (vertebrate)
Hagfish - bottom-dwelling marine scavenger, have slime glands that secrete slime that covers gills and suffocates predators
Lampreys - parasites of live fish
Describe gnathostomes and what are the two clades we need to know?
“Jawed fishes”
2 Clades: Chondrichthyans and Osteichthyans
Describe the clade of chondrichthyans (gnathostomes).
Shark, stingray, ratfish
Cartilagenous fishes
uncovered gill slits
Go in depth on sharks (gnathostome: Chondrichthyan)
ampullae of lorenzini: detects electrical fields of nearby animal (for predation), located around the sharks nose
Most are predators, some of the largers ones are suspension feeders
Three ways embryos can develop (all internal) (will be described in another card)
have a cloaca - reproductive, excretory, and digestive tract all empty into common area
Describe the three ways a sharks embryo can develop.
Oviparous - Eggs hatch outside the mothers body
Ovoviviparous - embryo develops within the uterus and is nourished by the egg yolk
Viviparous - Embryo develops in the uterus and is nourished through a yolk sac placenta from the mothers blood
Describe osteichthyans (gnathostomes).
Bony fishes (and tetrapods)
gill slits covered with bone (operculum)
lateral line system - tactile sensory organ that detects movement and pressure changes in water
Swim bladder (needed because bone weighs fish down)
Oviparous - Lay eggs
What are the two types of osteichthyans (gnathostomes) we talked about in class?
Ray-finned fish - fin derived from skin, most fish are ray-finned (tuna, mudskipper, lionfish, seahorse, fine-spotted moray eel)
Lobe-finned fish - thick and fleshy fins supported by bones. Can swim and “walk” underwater. (coelacanths, lungfishes, tetrapods)
What is the huge thing that happened for vertebrates about 365 million years ago?
fins of some lobe-finned fish became limbs and feet of tetrapods.
What are the characteristics of a tetrapod?
- Four limbs and feet w/ digits
- Neck that allows head movement separate from body
- fusion of pelvic girdle to backbone
- absence of gills
- ears for detecting airborne sounds
What are the benefits to life on land?
Escape from aquatic predators
Access to new resources
What is the significance of Tiktaalik?
nicknamed fishopod
showed both fish and tetrapod characteristics, as well as a transition to life on land
What were the tetrapod and fish characteristics of Tiktaalik?
Fish: fins, gills and lungs, and fins
Tetrapod: Neck, ribs, fin skeleton, flat skull, eyes on top of skull
what are the three orders of amphibians (tetrapod)?
Urodela - have tails
Anura - no tails
Apoda - no legs
Describe Urodela (tetrapod: amphibian).
Salamanders and newts
Axolotl show paedomorphosis - the retention of juvenile features in sexually mature organisms
Describe Anurans (tetrapod: amphibian)?
Frogs
Lack tails and have powerful hind legs for locomotion on land
Frogs with leathery skin are toads
Describe Apoda (tetrapod: amphibians).
Resemble worms
absence of legs in secondary adaptation
nearly blind
Describe some of the features of amphibians.
Cutaneous breathing - skin aids lungs in gas exchange
Tadpoles: lack legs but eventually grow legs, lungs, ears, and predatory adaptations come during metamorphosis
How do amphibians fertilize eggs?
Outside of the body mostly, require a moist environment
In some species the male or females carry their eggs in their mouth, gut, or backs.