Postlab 2 - Protochordates and the Origin of Craniates Flashcards
characteristics of protochordates
- bilateral symmetry
- pharyngeal slits
- notochord
- dorsal hollow CNS
- postanal tail
- endostyle
subset of the larger group of animalia and share common features in development
basal deuterostomes
- Cambrian to present
- starfish, sea urchins, sea cucumbers, sea dasies, and crinoids
- presence of calcium carbonate skeleton
- presence of a secondary radial symmetry except in the most basal members
Echinoderms
proposed the establishment of Phylum Chordata
Ernst Haeckel (1874)
Different classes under Urochordata
- Ascidiacea
- Larvacea
- Thaliacea
sea squirts
Ascidiacea
larvaceans
larvacea
thaliaceans
thaliacea
lancelet or amphioxus
cephalochordata
- acorn worms
- marine organisms that live in the mud under shallow waters; fragile when handles; 1.5 m
- with invertebrate and chordate features
hemichordates
added acorn worms to Phylum Chordata
Bateson (1884)
why did Bateson add acorn worms to Phylum Chordata
- dorsal, hollow NS
- gill slits
- stomochord
- short diverticulum of the gut
- not homologous with the notochord
stomochord
parts of the acorn worm
- proboscis
- collar
- trunk
different parts of acorn worm trunk
- branchiogenital
- hepatic
- abdominal
- marine chordates
- notochord is confined to the locomotor tail of the free-living larval stage and lost during metamorphosis into sessile adults
- encolsed within a delicate, nonliving, and colored transparent tunic
- filter feeders
- possess pharyngeal slits
urochordata
Superclass under Subphylum Vertebrata
- Pisces
- Tetrapoda
Classes under superclass Pisces
- Agnatha
- Placodermi
- Chondrichthyes
- Acanthodii
- Osteichthyes
Subphylum Cephalochordata:
- all trunk; muscle segments that lie just under the skin
- myomeres extend the entire length of the organism
locomotor musculature
Subphylum Cephalochordata:
Skin
- single layer epidermis
- thin dermis
- cutaneous respiration
Subphylum Cephalochordata:
- opens into the atrium which surrounds the pharynx laterally and ventrally
- water that enters the pharynx is another source of oxygen
pharyngeal slits
Subphylum Cephalochordata:
- extends from tip to the rostrum to the tip of the tails
- muscular disc arranged like a long roll of coins separated by fluid-filled spaces
- adaptation that facilitates burrowing in the sand
notochord
what does the notochord support in Subphylum Cephalochordata
- pharyngeal bars
- buccal cirri
- mid-dorsal fin-like ridges
Subphylum Cephalochordata:
what lines the central canal
ependymal cells
Subphylum Cephalochordata:
surrounds the brain and spinal cord
leptomeninx
Subphylum Cephalochordata:
Food processing organs
- vestibule
- wheel organ
- buccal cirri
Subphylum Cephalochordata:
creates a steady flow of water through the mouth and into the pharynx
cilia
Subphylum Cephalochordata:
collective chamber of seawater
vestibule
Subphylum Cephalochordata:
covered with sticky mucus; retrieves some of the heavier food particles which directs it to the mouth and pharynx
wheel organ
Subphylum Cephalochordata:
partially strain water as it enters the vestibule
buccal cirri
monitor the food that enters
chemoreceptors
Subphylum Cephalochordata:
not prominent cavity in adult
coelom
Subphylum Cephalochordata:
termination of venous system; beginning of arteries; not a pump
sinus venosus
Subphylum Cephalochordata:
Organs associated with eliminatio of metabolic waste
- cyrtopodocytes
- pedicels
- nephridial tubule
- flagellum
Subphylum Cephalochordata:
cells that collect the metabolic waste
cyrtopodocytes
Subphylum Cephalochordata:
footlike projections that make contact with an adjacent glomerulus (arterial rete)
pedicels
Subphylum Cephalochordata:
collects fluid from a cluster of cyrtopodocytes and empty into the atrium
nephridial tubule
Subphylum Cephalochordata:
from cyrtopodocyte that propell tubule fluids to the atrium
flagellum
Subphylum Cephalochordata:
bulge into the atrium into which sperm or egg are shed
gonads
Subphylum Cephalochordata:
how are gametes flushed into the sea
via atriopore
ovaries and testes do not develop n the same individual
dioecious
Classes under Superclass Tetrapoda
- Amphibia
- Reptilia
- Aves
- Mammalia