Practical #3 - Protostomes and Deuterostomes Flashcards
1
Q
What is the difference between Protstome and Deuterostome, list the examples of each.
A
- Protostome - The blastopore becomes the mouth first
- Spiral and Determinate Cleavage
- Annelida, Mollusca, Arthropoda
- Deuterostomes - The blastopore becomes the anus first and then the mouth
- Radial and Indeterminate Cleavage
- Echinodermata, Chordata
2
Q
Give me the stages of early development in animals
A
- Zygote –> 2-cell stages –> 4-cell stage –> Morula –> Blastula (hollow ball called blastocoel) –> Gastrula
- blastopore is the opening of the gastrula
- blstocoel is the hollow center of a blastula
3
Q
Describe radial vs sprial cleavage
A
- Spiral - the successive planes of cell division in early development are not at right angles
-
Raidal - in most deurterostomes
- the planes of division are at right angles
- The tiers of cells stack up on top of each other in the early embryo
4
Q
Determinate vs Indeterminate Cleavage
A
-
Determinate - the developmental fate of each cell is determiend early on.
- You will not get identical twins of a cell is split in half. You will get tow “halves”
-
Indetermiante - Fates of the early cells do not become ‘fixed’ until later in development
- You can get identical twins
5
Q
What is the difference between Enterocoeloms and Schizocoeloms?
A
- Schizocoelom - solid masses of mesoderm form near the blastopore and these mases split open–forming a fluid filled body cavity
- Enterocoelom - masses of mesodermal cells ‘bud’ off of the wall of the archenteron to form enterocoelom
6
Q
What are the key characteristics of Phylum Annelida?
A
- Protostomes
- Pronounced Segmentation
- Metamerism - identical body compartments along the lengh of the body = metameres
-
Complete Digestive System
- Typhlosole- ridge-like fold of the intestine into the lumen = increase surface area
- Possess Metanephridia - opens at two ends: one to the outside and one to the coelom
- Closed Circulatory system - with blood vessels and heart
- NO respiration - just diffusion aross body wall
- Cephalization - brain, ventral nerve cord, ganglia
- Circular and longitudinal Muscles
-
Cuticle prevents dessication
- Coelomic compartments that serve as hydrostatic skeleton
- Posses Trocophore larvae
7
Q
Why is metamerism important evolutionarily?
A
- Because it allowed specialization of body parts.
- It allowed for separate hydrostatic compartments, which in turn allow for greater behavioral complexity and locomotion
8
Q
How is the metanephridia strcutred and how does it differ from the protonephridia?
A
- Metanephridia has 2 parts
- Nephrostome - connects the coelom to the metanephridia
- Nephridiospore - Connects the metanephridia to the outside
- Porotnephridia are close tubes with an opening to the outside
- Metanephridia are larger, more complex structures that often function in both excretion and osmoregulation
9
Q
How does reproduction Differ in Annelids?
A
- Oligochaetes and leeches are monoeciuos
- Polychaetes are dioecious
10
Q
What are the different classes of Phylum Annelida?
A
-
Class Polychaeta
- Mainy hairs per segment
-
Class Oligochaeta
- two pairs of hairs per segment
-
Class Hirudinea
- Oral and caudal suckers
11
Q
What are the Key Characteristics of Phylum Mollusca
A
- Protsome with sprial cleavage
- Four distinct body parts
- Head, Muscular Foot, Visceral mass, Mantle (which produces the shell if present)
- Skin is usually 1 cell layer thick and ciliated
- Use hydrostatic Skeleton to move appendages
- The foot - uses muscular contractions th move the bottom of the foot
- Extracellular Digestion - Chitinous ribbon of teeth called- radula
- Possess metanephridia
-
Open Circulatory System - blood filled cavity called a hemocoel
- Cehpalopods have a closed system
- Well developed nerve system with ventral nerve cord, brain and ganglia
- Use gills for gas exchange….some land snails have lungs
- Can be monoecious or dioecious with internal or extenal fetilization
- Also have the trocophore larva
- Basic immune system with integument, amebocytes (phagocytize things)
12
Q
Which class of Mollusca is not bilaterally symmetrical and cephalized?
A
Bivalves
13
Q
What are the 4 classes of Phylum Mollusca
A
-
Class Bivalvia
- Two shells (clams, scallops, mussels
- Dreissena
-
Class Gastropoda
- Named for ventral location of foot (snails and slugs)
- Physella
-
Class Polyplacophora
- 8 calcareous plates (The chitons)
-
Class Cephalopoda
- most have well developed brain (octopi and squid)
14
Q
What are the key characteristics of Phylum Arthropoda?
A
- Protostomes
- Coelom is a body cavity called hemocoel
-
Segmented body plan - segments fused into tagmata
- head, thorax, abdomen
- Jointed appendages called podomeres
-
Exoskeleton composed of chitin
- Can molt and undergo ecdysis allowing growth
- Extracellular digestion
- Green Glands or Malpighian Tubules- for osmoregulation and exxretion
- Open Circulatory System - uses fluid called hemolymph instead of blood
- Respiration 3 forms
- Gills, tracheae, Book lungs
- Anterior brain, paired ventral nerve cord
- Normally dioecious with internal fertilization. Metamorphosis is common
- Non specific immune system with amebocytes
15
Q
What is the difference between green glands and Malpighian Tubules?
A
-
Green Glands
- type of nephridium that exretes large amounts of ammonia and water
-
Malpighian Tubules
- blind tubes that dump nitrogenous waste and water into the gut
- The gut then reabsorbs water and the uric acid is eliminted with with other stuff
- Since less water is need, uric acid is insoluble in water, it allows for arthropods to colonize land!
