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Biology Class Notes: Invertebrates (part 2) - Symmetry, Body Plans, and Phyla - Prof. Ray , Study notes of Biology

Announcements, questions, and figures from a biology class on invertebrates (part 2), covering topics such as symmetry, body plans, and phyla. It includes information on sponges, cnidaria, porifora, radiata, bilateria, triploblastic, lophotrochozoans, platyhelminthes, mollusca, annelida, and arthropoda.

Typology: Study notes

2011/2012

Uploaded on 05/13/2012

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1/23/2012
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Invertebrates (part 2)
Announcements
PRS Friday & Today’s scores posted by this evening
Friday deadline for sorting out problems
Homework & Quiz homework NOT turned in, but must be
completed for successful completion of online Quiz
Tutoring Schedule posted on MyCourses info posted on
MyCourses
Mastering Biology website info posted on MyCourses
later today
Review Session 4pm tomorrow in Newton 203
Bilateral symmetry is LEAST associated
with
A. cephalization.
B. the presence of mesoderm.
C. an active lifestyle.
D. a nervous system with sensory structures
concentrated at one end of the animal.
E. the sessile condition.
Why do sponges represent a separate
lineage, distinct from all other animal
phyla?
A. They are sedentary and resemble plants.
B. Most individuals are hermaphrodites.
C. They lack true tissues.
D. They do not have specialized cell types.
E. They have only two layers of cells.
Cnidaria includes groups with a variety
of body forms, but all share which
common feature?
A. All are filter feeders.
B. All live in tropical oceans.
C. All are strong swimmers.
D. All have a gastrovascular cavity and tentacles.
E. All reproduce mainly asexually.
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Invertebrates (part 2)

Announcements

  • PRS – Friday & Today’s scores posted by this evening
    • Friday deadline for sorting out problems
  • Homework & Quiz – homework NOT turned in, but must be completed for successful completion of online Quiz
  • Tutoring Schedule posted on MyCourses – info posted on MyCourses
  • Mastering Biology website – info posted on MyCourses later today
  • Review Session 4pm tomorrow in Newton 203

Bilateral symmetry is LEAST associated

with

A. cephalization. B. the presence of mesoderm. C. an active lifestyle. D. a nervous system with sensory structures concentrated at one end of the animal. E. the sessile condition.

Why do sponges represent a separate

lineage, distinct from all other animal

phyla?

A. They are sedentary and resemble plants. B. Most individuals are hermaphrodites. C. They lack true tissues. D. They do not have specialized cell types. E. They have only two layers of cells.

Cnidaria includes groups with a variety

of body forms, but all share which

common feature?

A. All are filter feeders. B. All live in tropical oceans. C. All are strong swimmers. D. All have a gastrovascular cavity and tentacles. E. All reproduce mainly asexually.

Figure 33.4 Anatomy of a sponge •^ Cnidocytes^ = stinging cells for prey capture & defense

  • Stinging cells have nematocysts

Important Links between Form and

Function

  • Shared “body plans” among animals in a grade are linked to special challenges of their environment
  • Porifora & Radiata
    • Different body plans
    • Specialized for food capture
    • Very efficient at food capture even without “directed forward motion or pursuit of prey” - Next major branch point: - Bilateria divided into: - Deuterostomes - Lophotrochozoans - Ecdyzoans What does it mean to be Triploblastic?
  • A. To have three pairs of fins or limbs
  • B. To go through 3 major phases during development
  • C. To have at least 3 planes of symmetry
  • D. To have 3 germ/tissue layers
  • E. To have 3 body cavities What morphological characters do Lophotrochozoans all share?
  • A. True tissues
  • B. Choanocytes and/or cnidocytes for capturing food
  • C. Trochophore larvae or Lophophores for capturing food
  • D. Both A and C
  • E. Both B and C
  • F. A and B and C

Molluscan Body Plan

  • Mantle
    • Tissue that secretes the shell
  • Visceral Mass
    • Contains most internal organs
    • open circulatory system
  • Foot
    • Muscular, for movement or 8 classes – you need to know 3 attachment Gastropods, Bivalves, Cephalopods

Class Gastropoda

  • Snails & Slugs – largest class
  • Torsion
    • During development one side of visceral mass grows faster
    • Result: mantle cavity - over the head
  • Most have single spiral shell
  • Most are grazers – impt. herbivores in their habitat

The Gastropods The Bivalves^ Clams, oysters,

mussels Marine & freshwater Shells divided into 2 halves Bivalves are filter feeders Often use their foot as an anchor Many play important ecological roles Eg. Zebra mussels

Class Cephalopoda

  • Predators
  • Foot modified into tentacles,head & excurrent siphon
  • Shell reduced or missing in most cephalopods
  • Very well developed sense organs & complex brains – linked to predatory lifestyle?

BILATERIA: Lophotrochozoans

  • Phylum Platyhelminthes - flatworm
  • Phylum Mollusca – mollusks
  • Phylum Annelida – annelids (segmented worms)

Phylum Annelida

True Coelom is divided into compartments by septa: segmented body Muscles run longitudinally & circularly – distinctive movement Nervous system Gut tract w/ specialized regions Closed circulatory system

Ecological Roles of Earthworms

  • Aerate & fertilize soil
  • What about earthworm invaders?
  • In northern N.A. earthworms disappeared during the last glaciation event (>10,000 y.a.)
  • Reintroduced by European settlers
    • changed ecology of the Northern Hardwood forests

Effects of exotic earthworms in Minnesota

Figure from: Minnesota Worm Watch http://www.nrri.umn.edu/worms/forest.html

What three body parts do all Molluscs

share?

  • A) foot, visceral mass, mantle
  • B) mantle, gills, tentacles
  • c) foot, visceral mass, shell
  • d) none of the above

The Ecdysozoans

  • Nematoda
  • Arthropoda
    • Hard, cuticle body covering
    • The cuticle is shed or molted through a process called ecdysis

Nematode Characteristics

  • Pseudocoelomate
  • Epidermis excretes a cuticle covering
  • Muscles underneath – run lengthwise along body
  • 2 nerves – muscles branch towards nerves http://nematode.unl.edu/ - Peter Mullin