Biology 202 Lab Practical #1 Review
Lab 1: Lab Intro and Phyla Porifera ( Calcarea, Hexactenelida &Spogin) and Cnidaria( Hydrozoa &
- What is an invertebrate? An animal that lacks a back bone. Much great number and diversity of
invertebrates versus vertebrates. They share basic characteristics of : soft bodies or
exoskeletons, ventral nerve cords and dorsally located hearts ( only the more advanced species).
Phylum Porifera (Sponges)
- Sessile ( adhere to a substrate) & often encrust rocks. Can be up to a meter in length ( large
glass sponges). Multicellular but do not exhibit a true tissue system. Body organized around a
pore or canal system which they pump water through.
- Most typical cell is the flagellated Choanocyte, or collar cell. they use this to circulate water
through their pores allowing them to filter feed.
- Sponges are divieded into groups based on the type of spicules in their skeleton. The 3 classes
are: bony ( the Calcarea), glass (the Hexactenellida), and spongin (the Demospongiae, represent
at least 80% of all sponges).
- FIGURE 1.1 = Body wall of a sponge. Pointy stars= spicules, Lipid looking cells = Chaoncytes,
intercellular fluid= mesophyll, Outer coating = epidermis, canals into the cell body= porocytes.
- Simplest Eumetazoa (organism that have clearly recognizable tissues and/or organs), Radially
symmetrical or Bilaterally symmetrical. Often occur in two forms: a tubular , blind sac the Polyp
with tentacles surrounding the mouth or the Medusa, or jellyfish also with tentacles.
- Class Hydrozoa: Asexual Polyps and Sexual Medusae.
- Cross section of a hydra: Inner cavity= gastrovascular cavity, Inner layer of cells= gastrodermis,
division of inner and outer layers= mesoglea, darker cell with a tail = Cnidocyte ( the tail , used
for prey capture and defense is the Nematocyst)
- Class Scyphozoa: Emphasizes the Medusoid sage. Longitudinal septa in gastric cavity. Life cycle:
1) Planula, the typical larvae with solid multicellular form with a ciliated exterior. 2) it then
settles and develops into the Scyphistoma. 3) that then forms a Strobila , a series of saucerlike
buds or Ephyrae. 4) the Ephyrae is the immature Medusa, so they will mature into a full jellyfish.
- Class Anthozoa: exclusively attached polyps ( sea anemones and corals), gastric cavity divided by
septa. Two Subclasses: 1) Acyonaria ( soft corals, sea fans and sea pens). 2) Zoantharia ( black
corals, stony corals ).
Lab 2: The worms- Phyla Platyhelminthes (Turbellaria , Cestooidea & Trematoda), Nematoda and
Annelida ( Clittellatea [ Oligochaetes & Hirudinea] & Polychaeta) - Distant relatives but they allows for the study of Coeloms (body cavities), Segmentation and
Organ Systems. All Bilaterally symmetrical.
- Class Turbellaria (Most marine free living flatworms): Larval stages exhibits brief planktonic
state. Whole mount: Eyespot= dark spots near the arrow shaped end of body. Pharynx= ridge
the back of organism. Gastrovascular Cavity= open area in the tail portion of organism. Cross
section: Epithelium= lining of the inner cavitys. Parenchyma = intercellular fluid. Circular muscle
layers: wraps around the pharynx. Pharynx= central ring. Intestines= Smalller rings alongside of
the pharynx. Ciliated epidermis= outer covering with small projects ( on the underside).
Pharyngeal cavity = central cavity. Longitudinal muscles= muscles running length wise on the
- Class Trematoda ( Flukes): all parasitic, major medical and economic importance, complex multi
host lifecycles, Specific adaptions for parasitic life. Whole Mount: Suckers= round openings
towards the front( narrowest part) of the organism. Testes= thick tubes located away from the
suckers. Uterus containing eggs= Smaller bundle of tubes, centrally located. Intenstine= tubes
running the length of the organism. General Lifecycle: Eggs Miracidia Rediae Adult.
- Class Cestooidea ( Tapeworms) : parasites, complex life cycles, complex head or scolex and
ribbion like body composed of proglottids ( a chain of them allows for packaging and distribution
of the gonads. 4X magnification of speciement: Scolex= Small round end to the segments.
Neck= long first segment. Immature Proglottid= segment that look empty or light in color.
Mature Proglottid= segment being to fill up with gonads, organs still visible, darker in color.
Gravid proglottid= about to burst packed with gonads, very dark in color. 10X magnification:
Genital Pore: small opening + tube , connected to the ovarys, Ovaries= small clusters within at
the end of the genital pore tube, Uterus= darker spots located around the ovary. Testes= small
cirlces around everything.
- Roundworms, both free living and parasitic , first organisms to shows a complete digestive tract,
coelom not completely lined with peritoneum ( pseudocoel)
- Nematoda: Whole mount: Mouth= flatter end, cuticle = outer covering, anus= narrower end
(hooked on males). Male Cross section: testes= dark grouping of small masses with a ring
aroung them. Intestine= long whiteish string. Female Cross section: Uterus= large mass of dark
dots, non-uniform edge. Ovaries= round or oval shape with visible difference in the center
(looks like a donut).
- True coelom, well developed organ systems , display segmentation (metamerism), increased
cephalization, well developed nervous system and closed circulatory system
- Class Clittellatea: Oligochaetes ( earthworms) have bristles or setae in small bundles, lack