Bio 123: PP15 Material Flashcards
What are the 4 key characteristics of Chordates?
1) There is a presence of notochord
2)The nerve cord runs parallel with the notochord and gut, anterior end develops into the brain
3)Gill slits penetrate the wall of a pharynx (at least at some point in embryological development)
4) Tail extends past the anus (at least at some point of their development)
*** All of these features are present is chordate embryos
Do all vertebrata have vertebrates?
NO
What are 2 basic characteristics of Chordates?
They are coelomate and demonstrate bilateral symmetry.
What is the Notochord?
It is a rod of stiffened, but flexible, tissue that helps support the body.
The notochord also later develops into the vertebral column
What are some characteristics of the bodily systems of chordates?
-They have a defined central nervous system
-The pharynx moves from a digestive tract to a respiratory organ
What are the 3 major sub-phyla of chordates?
1) Urochordata (invertebrates)
2) Cephalochordata (invertebrates)
3) Vetebrata
What is a distinguishing characteristics of the vetebrata?
The vertebral column evolves from primitive notochord, composed on individual vertebral bones and are separated by disks (ligaments)
What is the common name for Urochordata?
They are known as sea squirts or tunicates.
What are the characteristics of Urochordata?
-Is the most ancestral sub-phylum of chordates.
-They begin as bilateral larvae swimmers
-Adults display evolutionary reversals
-They have a jellylike tunic around the pharynx
-Most are a few centimeters long
-Live in a variety of aquatic habitats
-Are filter feeders and have an incurrent and outcurrent siphon, gill slits
-The pharynx is a respiratory organ as well
-Gas exchange is done through diffusion
What are some reversals that we see in adult Urochordates?
-Their tail is reabsorbed
-They take on more of a radial symmetry
-Their nerve cord is absorbed into their body
-They gather oxygen through diffusion
-Have a basic circulatory system
What is the tunicate?
The larva form of urochordates
What are the characteristics of Cephalochordata?
-Closets relatives to Vertebrata
-Only 3-7 cm long
-Body display all chordate features throughout their life
-Have a head and a simple brains with neurons
-Have segmented muscles
-Are filter feeders
-Nerve cord sits dorsal to the notocord
-Tail is used for balance
What are some major body characteristics of Cephalochordata?
-Have an eyespot
-Tentacle like structures around the mouth
-Dorsal tubular nerve cord
-Notocord
-Pharynx with gill slits
-tail extending past anus
What are the myomeres?
They are each segmented muslce
What are the characteristics of Vertebrata?
-Pharynx completely shifts to gas exchange
-Accessory digestive organs such as the liver and pancreas
-Have chambered hearts
-Have tripartite brain
-Have advanced sensory structures (increased cephalization)
-Have an affinity for oxygen in red blood cells (hemoglobin)
-Have kidneys
-Have an endocrine system
What does tripartite brain mean?
That the brain have a forebrain, midbrain, and hindbrain
What is the purpose of the liver in vertebrata?
It secretes bile and metabolizes protein, fats, and other substances
What is the purpose of the pancreas?
It regulates sugar levels in the blood
Define emulsification
The process in which large lipid globules are broken down into smaller lipid globules.
What classes fall under the sub phylum Vertebrata?
Myxini (Hagfish)
Petromyzontida (lamprey)
What is the ancestral state of hearts?
Having 2 chambers
What is the derived state of hearts?
Having 4 chambers (Birds and mammals have 4 heart chambers)
Excretory system
Is made of individual units known as nephrons that filter the blood and get rid of waste (bladder and kidneys included)
What is a unique characteristics of Myxini?
They are the most ancestral class within the vertebrata and their new characteristic is that they have a cranium
What is the earliest cranium made out of?
Cartilage
What are the characteristics of Myxini?
-Known as hagfish
-Do not have a true vertebral column
-First group with a cranium
-Cartilage protects their brain (no bone yet)
-Less that a meter long
-Nearly blind
-Finds found through sensory tentacles
-Are relatively sessile and have low metabolic rates
-unique predatory defenses
-Closely related to lamprey and have jawless lineages
Define the cranium
It is a hardened structure made out of cartilage that protects the brain.
What is the defense mechanism of hagfish?
They excrete a thick slime into the environment that basically clogs the gills of its predators which causes them to suffocate and die.
What is a new characteristic found in Petromyzontida?
Their new characteristic is that they have a true vertebral column
What are the characteristics of Petromyzontida (lampreys)?
- Become distinct due to the presence of a vertebrate (First true vertebrates)
-Are jawless
-Are parasitic
-Have a small cerebellum
-Have sensory structures such as eyes well, two-pairs of semicircular canals
-Well established in great lakes
-Defined CNS
What is the purpose of the cerebellum?
Responsible for balance and equillibrium
What are ammocoetes?
The larvae of petromyzontida (hagfish)
What is the life cycle of hagfish?
-M/F hagfish seek out riffle areas and create a crescent shaped nests with gravel and small stones
-They place their fertilized eggs among the gravel which hatch a few weeks later
-Larvae emerge from the nests and drift downstream.
-These larvae will burrow into silt and will remain there for 3-5 years until they mature.
-adult parasites will leave silt as sea lampreys and feed on fish.
*** each adult lamprey will spend 12-18 months in the lakes and destroy up to 40 pound of fish.
What are the ecological issues with hagfish?
Hagfish are a highly invasive species and they are causing a decline in the fish population in great lakes. It has commercial affects because fishing companies cannot take to market fish that have been bitten and there is a decrease in fish population.
What are the teeth of hagfish made out of?
Keratin
Explain the semicircular canals
Sensory structures that are the earliest development of ear canals
Vertigo
Sensation of feeling dizzy
Invasive species
Any species that moves into a havitat that is not native to them and they over compete against the native species
What are some physical features of hagfish?
-Eye
-Nostril
-Buccal tunnel
-External gill slits
- Anterior dorsal fin
-Caudal fin
-Tail
-Cloacal aperture
Lampricide
A pesticide used to try to control sea lamprey populations. This pesticide specifically targets the larval stage of the sea lamprey.
