Lecture 13

Question 1

Symbiosis in Cnidarians examples

Answer 1

• Obligate Mutualism
Anemonefish can’t survive without
protection of an anemone
• Facultative Mutualism
Sea anemones can survive without an anemonefish

Question 2

Symbiosis with Zooxanthellae algae

Answer 2

Coral gets energy from the zooxanthellae’s ‘photosynthetic leftovers

Question 3

Worm Phyla

Answer 3

• Phylum Platyhelminthes
• Phylum Nematoda
• Phylum Annelida

Question 4

Worm Body Plans

Answer 4

platyhelminthes- Acoelomate
Nematodes- Pseudocoelomate
Annelids- Coelomate

Question 5

Phylum Platyhelminthes characteristics

Answer 5

Commonly called ‘flatworms’
Most are parasitic
Triploblastic
Acoelomate
 Bilateral symmetry
Cephalization
Hydrostatic skeleton
Incomplete(‘blind’)gut
 Reproduction: Asexual and Sexual (usually monoecious)
“Tissue-Organ”level of biological complexity (no systems)

Question 6

How do platyhelminthes breathe

Answer 6

via diffusion

Question 7

Phylum Platyhelminthes Classes

Answer 7

• Class Turbellaria
      Mostly free living (not parasitic)
        e.g. planaria
• Class Cestoda
       Parasitic
      ex Tapeworms
• Class Trematoda 
         Parasitic
         Flukes

Question 8

Class Turbellaria Characteristics

Answer 8

• Only class of flatworms that has free-living members
• Some symbiotic
• Blind gut – waste ejected through mouth
• Sexual and Asexual Reproduction

Question 9

Class Cestoda: tapeworms body composition

Answer 9

Long flat body composed of…
• Scolex, for attachment to the host
• Strobila, main body composed of chain of proglottids
• Proglottids, reproductive units

Question 10

Class Cestoda characteristics

Answer 10

Class Cestoda= Tapeworms
• Nearly all monoecious
Proglottids fertilized by another proglottid on
the same or a different strobila
• Shelled embryos form in the uterus of the proglottid
• Strobilation
New proglottids form behind scolex
• Terminal gravid proglottids break off and are excreted in host’s feces

Question 11

Class Trematoda characterisitcs

Answer 11

Class Trematoda=parasitic flukes
Almost all endoparasites of vertebrates
leaflife body form

Question 12

Which class and species are in the phylum Platyhelminthes

Answer 12

Class Turbellaria species Flatworms
Class Cestoda species tapeworms
Class Trematoda species flukes

Question 13

What class and species are in phylum Nematoda

Answer 13

No class, species roundworms

Question 14

What class and species are in phylum Annelida

Answer 14

Polychaeta ,marine worms

Oligochaeta, earthworms

Hirudinida, leeches

Question 15

Phylum Nematoda Characteristics(11)

Answer 15

Phylum Nematoda= roundworm
• Triploblastic
• Pseudocoelomate
• Bilateral Symmetry
• Cephalization
• Hydrostatic skeleton formed by fluid filled pseudocoelom
• Ecdysozoans
• Have a molted cuticle (non-living external layer secreted by the epidermis)
• Complete gut
• Reproduction: sexual, most dioecious
• Organ-system level of biological complexity
• Have a full digestive system, but lack a circulatory system

Question 16

Differences between Nematoda and Platyhelminthes

Answer 16

Nematoda have:
       Pseudocoelomate
      Hydrostatic skeleton formed by fluid filled pseudocoelom 
       Ecdysozoans
        Have a molted cuticle

have a Complete gut
have organ systems (ie digestive system, no circulatory)

Platyhelminthes

• Acoelomate
• Cephalization
• Incomplete(‘blind’)gut
• Organ tissue

Question 17

Phylum Annelida characterisitcs

Answer 17

Phylum Annelida= earthworms, leeches,freshwater worms
• Triploblastic
• Coelomate
• Bilateral Symmetry, Cephalization, Hydrostaticskeleton
• Lophotrocozaoan
• Has trochophore larvae
• Complete gut
• Reproduction:Asexual and Sexual (monoecious or dioecious)
• Organ-system level of biological complexity
• Exhibit Metamerism
• Many have setae

Question 18

What is Metamerism

Answer 18

Worms have em
• Being composed of serially repeating parts;serial segmentation
• Segments are called metameres or somites
•Segments can be repetitive, but not identical
•Evolved differently in each group

Question 19

Benefits of Metamerism

Answer 19

Allows for greater complexity in structure and function possible

Question 20

Pseudometamerism

Answer 20

In tapeworms
Repeated segments are independent of each other
Each contains a complete set of organs

Question 21

Reproduction for Oligochaeta

Answer 21

Oligochaeta= earthworm
• Monoecious
• do not self-fertilize
• Mate on the surface (at night)

Question 22

Earthworm Reproduction -description

Answer 22

• Extend anterior ends from burrows, press ventral surfaces together
• Held together by mucus
Ventral setae also penetrate eachother’s bodies
• Sperm discharged and travels along the seminal groove (externally)
into the seminal receptacle of the other worm
• Worms separate
• Each worm secretes around its clitellum…
first,a mucous tube
then,a tough band that forms a cocoon
• Cocoon slides forward along body
• As it moves the following are mixed in the cocoon:
Eggs from oviducts(from genital pore)
Albumin(from skin glands)
Sperm from mate(stored in seminal receptacles)
• Fertilization of eggs occurs in the cocoon
• Cocoon slides off the head end of the worm
• Embryonic development occurs within the cocoon

Question 23

how to Polychaeta differ from other annelids

Answer 23

• Well-differentiated head
• Specialized sense organs
• Paired paddlelike appendages (parapodia)
• Many chaetae on each parapodium
• No clitellum

Question 24

Class Hirudinida characteristics

Answer 24

Leeches
• Fixed number of segments (usually 34)
• No parapodia or setae
• Variable dietary strategies:
• carnivores on small invertebrates
• temporary parasites: sucking blood from vertebrates
• permanent parasites: don’t leave host
• Monoecious, cross-fertilization
• Clitellum is evident only during the breeding season