Practical #3 - Animal Body Plans, Parazoas/Eumetazoas

Question 1

What is the difference between Parazoa and Eumetazoa?

Answer 1

• The presence or abscence of true tissues (layers of differentiated cells)

Question 2

Describe the characteristics of a diploblastic ogranism

Answer 2

• 2 Germ Layers:
  
  • Endoderm - innermost primary germ layer
  • Ectoderm - outermost primary germ layer
• Main Phylum Cnidaria

Question 3

Describe the characteristics of a Triploblastic Organism

Answer 3

• Posses 3 germ layers
  
  • Endoderm
  • Ectorderm
  • mesoderm - lies between the ectoderm and endoderm
    
    • Cells include the lining of the internal body cavity

Question 4

What is a Coelom?

Answer 4

• Internal body cavity

Question 5

What tissues/organs does the endoderm give rise to?

Answer 5

• Cells that line the digestive tract and its accessory organs (liver, pancrease).
• cells that line the respiratory tract in the lungs

Question 6

What cells/tissues/organs does the Ectoderm give rise to?

Answer 6

• The outer covering of the animal
  
  • Skin (or integument)
• accessory organs associated with skin

Question 7

What cells/tissues/organs does the mesoderm give rise to?

Answer 7

• cells between the integument and difestive tract
• Lining of the internal body cavity, muscle cells, various parts of the circulatory system
• Cells of endoskeleton
  
  • cartilage and bone
  • Excretory organs, various glands and reproductive organs

Question 8

What are the 4 body plans for Eumetazoans?

Answer 8

• Diploblastic acoelomates
• Triploblastic acoelomate
• Pseudocoelomate
• Coelomates (Eucoelomates)

Question 9

Describe a Diploblastic Acoelomate.

Answer 9

• Do not posses and internal body cavity (or coelom)
• Lack a mesoderm
• Ex: Cnidarians

Question 10

Describe a Triploblastic Acoelomate

Answer 10

• Still does not possess a coelom
• The region between the difestive tract and out body wall is filled with mesodermally derived cells
• Ex: Platyhelminthes (Flatworms)

Question 11

Describe a triploblastic pseudocoelmate

Answer 11

• Possess a fluid filled vacity, but the cavity is incompletely lined with mesoderm-derived tissues
• Ex: Phylum Nematoda

Question 12

Describe Triploblastic Eucoelomate

Answer 12

• Coelom is a dluid-filled cavity completely lined with mesodermally-derived cells
• Several organ systems suspended within the coelom
  
  • mesenteries

Question 13

What are the advantages to having a coelom

Answer 13

• Room for organs to grow and develop
• Increased surface area for gas exchange and nutrient transport into and out of organs
• Hyrostatic skeleton for support, locomation
• place to store materialsRoute to pass nirtogenous wastes and gametes to the outside

Question 14

What is the difference between radially and Bilateral symmetrical bodies

Answer 14

• Radial Symmetry - can be divivded by many planes through the central axis of its body running from top to bottom
  
  • No distinct head, or right and left sides.
• Bilateral Symmetry - they may be divided into two mirror halves only through one longitudinal plant
  
  • median plane (or midsagittal plane)
  • ​Transverse plan - divides the body into superior (anterior) and inferior (posterior)
  • Frontal Plan (coronal plane) - divides the body inoto a front (Ventral) and back (Dorsal)
  • Sagittal plane - divides the body into left and right sides
  • Coevolved with cephalization!

Question 15

Which classes are in Phylum Porifera (sponges)?

Answer 15

• Class Calcarea
  
  • ​Calcareous sponges
• Class Hexactinellida
  
  • ​Glass sponges
• Class Demospongiae
  
  • ​Bath sponges

Question 16

Which classes are in Phylum Cnidaria?

Answer 16

• Class Hydrozoa
  
  • Hydras
• Class Scyphozoa
  
  • Jellyfish
• Class Anthozoa
  
  • Sea anemones

Question 17

What classes are in Phylum Platyhelminthes (flatworms)

Answer 17

• Class Turbellaria
  
  • Planarians
• Class Trematoda
  
  • Flukes
• Class Cestoda
  
  • Tapeworms

Question 18

What are the key Characteristics of the Poriferas

Answer 18

• Cellular level of organization
  
  • no tissues/organs and asymmetrical
• Somatic regeneration - isolated cells can make a new sponge
• Cells are totipotent - each cell can give rise to any other cell type
• no germ layers, digestive tract, coeloms
• Choanocytes - flagellated cells used in digestion and movement of water
• No cephalization
• Marine

Question 19

What are the sponges made of?

Answer 19

• The internal skeleton is made of spicules
  
  • Siliceous (Glass)
  • Calcareous (calcium carbonate
• Some species have a network of proteinaceous fibers
  
  • spongin

Question 20

Describe How Sponges move water/nutrients through their body

Answer 20

• Water enters incurrent canals through outer pores called ostia
• Water then moves through internal pores (prosopyles) that connect incurrent canal to radial canal
• Choanocytes line the radial canals
• Water then leaves the radial canals through small pores (apopyles) and enters the spongocoel
• Water exits the spongocoel through large single opening of the osculum

Question 21

How do choanocytes aid in digestion in the Poriferas?

Answer 21

• The water currents are formed by the beating of flagella
• Sponge cells excahnge gases and expel wastes as water passes by
• digestion occurs in the choanocytes
• Intercellular digestion
  
  • pinacocytes - thin cells ling the outsid of spong
  • Amebocytes - amoeboid cells involved in intracellular digestion
    
    • scattered through gel-like matrix called mesohyl

Question 22

How do sponges reproduce?

Answer 22

• Amphiblastulas - clusters of sponge larvae
  
  • formed by fertilization of egg
• fragment and Budding

Question 23

What are the key characteristics of Phylum Cnidaria?

Answer 23

• Diploblastic Acoelomate
  
  • 2 tissues - epiderms and gastrodermis
  • mesoglea - layer between the two dermal layers
• Unsegmented
• Radial Symmetry
• 2 distinct body forms
  
  • Polp and Medusa
• Some colonial cnidarians have a perisarc - outer layer of protection
• Cnidocytes - stinging cells on the tenticals
  
  • nematocyst
• Digest occurs extracellular in gastrovascula cavity
• No respiratory system - diffusion
• No osmoregulatory sytem - diffusion
• Posses a simple Nerve-Net, no brain
• Reproduce asexually by budding
  
  • ​Normally dioecious - if reproducing sexually

Question 24

How to Cnidarians move about?

Answer 24

• Muscles in the epiderms (epitheliomuscualr) and in the gastrodermis (nutritive-muscular cells) are capable of contraction

Question 25

What are the key characteristics of Phylum Platyhelminthes?

Answer 25

• Dorosventrall falttened body
• Triploblastic Acoelomate, Bilaterally symmetrical
• Posses distinct tissues and organs
• Osmoregulatory System - consisting of protonephridia
• No respiratory system, no circulatory system
• Incomplete Digestive Tract - one opening
  
  • Extracellular and then intracelluar
• Cephalization -
  
  • Cerebral Ganglia
  • Sensory and Moror Neurons
• Free living carnivores or parasites
• Typically monoecious - but need fertilization from another guy
• Have distinct skin or integument
  
  • ​Move by ciliary action

Question 26

What are the Key characteristics of Phylum Nematoda

Answer 26

• Round worms, unsegmented
• pseudocoelom, triploblastic, bilaterally symmetrical
• Cephalization
• Eutely - every individual consists of exactly the same number of cells
• Muscular System - longitudinal muscles
  
  • Muscles send processes to the nerves…not the other way around
• Complex digestive tract - two openings
  
  • Extracelllar digestion followed by intracellular
• Possess a noncellular cuticle (containing chitin) - this is shedded through molting
  
  • ​must stay in moist environments - allows water/oxygen to pass through
• No respiratory system
• No circulatory system
• Digestion - use a series of excretory canals
  
  • ​Use Renette Cells - absorb nitrogen and then can be passed through a pore outside
• usually dioecious
• Use a hydrostatic skeleton - provide strucutre against how muscles work