BIO 104 4/29/96

LAB LECTURE: INVERTEBRATES

TEXT ASSIGNMENT- Read Chapter 29, pp 544-569 in Raven & Johnson; you may
want to review Chapter 17, pp323-341 and Chapter 25, pp 476-490 in Raven &
Johnson to review.

OBJECTIVES
1) to observe the great diversity among invertebrates
2) to place invertebrates in their evolutionary context
3) to relate the different groups of invertebrates to the environments in
   which they are found
4) to understand the economic importance of invertebrates

CLASSIFYING ANIMALS (Refer to Lecture Notes 4/3/96 and 4/4/96)
   Kingdom   (Fungi, Monera, Protista, Archaebacteria, Plantae, Animalia)
   Phylum
   Class
   Order
   Family
   Genus
   Species

Dr. Barstow gave you the example of humans: Kingdom: Animal
                                            Phylum: Chordata
                                            Class: Mammalia
                                            Order: Primata
                                            Family: Hominidae
                                            Genus: Homo
                                            Species: sapiens

This week in lab: Kingdom: Animalia
     Phylum(s): Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca,
     Annelida, Arthropoda, Echinodermata

This week in lab: Evolutionary tour through the invertebrates -- A lot of
observing will be going on!  ***LAB NOTE - WE ARE WORKING WITH LIVING
CREATURES, TREAT THEM WITH RESPECT!!!***

CHECKLIST of observations for working through this lab

NOT SO VISIBLE things to know (i.e. check your textbook or lab manual):
1. Organization - Is the animal composed of cells, tissues, organs, or
   organ systems?
2. Type of body cavity - acoelomate, pseudocoelomate, coelomate?
   acoelomate - no body cavity - 
   pseudocoelomate - has a body cavity which isn't formed from mesoderm 
   coelomate - true body cavity formed from mesoderm and supported by mesenteries
3. Is the phylum protostome or deuterostome in development?
   protostome - blastopore (1st opening from ball of cells) becomes mouth
   deuterostome - blastopore becomes anus - 

VISIBLE things to observe
4. What type of symmetry? Radial or bilateral.
5. Is their cephalization? Meaning -- does it have a head?
   Cephalization is important because it allows for a concentration of
   sensory neurons or in other words a brain!
6. Is their segments or specialized regions of body function?  Segmentation allows for
increased specialization in body function -- kind of a "division of labor"
7. What type of skeleton? 
   Hydrostatic - uses water of its environment or the pressure of internal
   body fluids.
        Advantages: use what you've got available - bring in food at the
        same time-squeeze into tight spots in your habitat
   Exoskeleton - external framework
        Advantages: protection- water proofing (helps in becoming terrestrial)
        Disadvantage: tough to grow - molting
   Endoskeleton - like us - internal framework
        Advantages: unrestricted growth
8. How does the animal function in its environment? Is it immobile, fixed
   in place (sessile) or is it mobile? 
9. What about its ecology? Is it a parasite, a disease carrier, a cool thing
   to eat, an important economic resource of any kind? 

SURVEY OF PHYLA CONTINUED

VI.  Phylum Arthropoda -includes horseshoe crabs, spiders, scorpions, mites, ticks
shrimp, crabs, lobsters, pill bugs, centipedes, millipedes, insects!

How do these all fit together? The answer is that classification scheme I reviewed at
the start of this lecture. You don't need to memorize this! This is simply to help you
better understand the diversity that gets lumped as Arthropods.
   Phylum Arthropoda
        Subphylum Chelicerata
             Class Merostomata = horseshoe crabs
             Class Arachnida = spiders, scorpions, mites & ticks
        Subphylum Crustacea
             Class Malacostraca = crabs and shrimps
        Subphylum Uniramia
             Class Chilopoda = centipedes
             Class Diplopoda = millipedes
             Class Insecta = insects!

A. Exoskeleton - reduces water loss, provides protection - Arthropods can be found
in all terrestrial habitats and exhibit extreme diversity in form and function.
B. Exhibit bilateral symmetry - highly developed cephalization.
C. Segments have fused to form body regions (tagmosis). The best example of this is
the insects : head, thorax,  abdomen
   head - sensory organs, variety of mouthparts
   thorax - space for the specialized muscles necessary for flight!
   abdomen - digestion, reproduction
*jointed appendages
D. Coelomate, Protostomes, complete digestive tract with mouth and anus
E. Importance to humans: disease vectors such as mosquitoes
                                   food - Crustaceans, honey from bees
                                   agriculture - some insects destroy
crops, some natural predators are being used as biological control agents
                                             pollinators 
                                             silk
                                             recyclers - out there in nature chewing up organic                                                matter, decomposing stuff, etc.

VII. Phylum Echinodermata - starfish, sand dollars, sea urchins, sea cucumbers,                                               brittlestars

A. Symmetry: Larvae = bilateral,  Adults = radial
B. Deuterostomes
C. Coelomate
D. Water Vascular System - food collection and locomotion
E. Endoskeleton with thin layer of epidermis on top
F. Regeneration - rip an arm off a starfish and it can grow a new one
G. Importance - food source, economic pest - predators on shellfish