Lab Practical 2 BIO 142

Porifera

Sponges (no true tissues).

Cnidaria

Jellyfish, corals, sea anemones, hydras.

Platyhelminthes

Flatworms (planarians, tapeworms, flukes).

Nematoda

Roundworms (C. elegans, pinworms, hookworms)

Mollusca

Clams, snails, octopuses, squids

Annelida

Segmented worms (earthworms, leeches, polychaetes)

Arthropoda

Insects, spiders, crustaceans (crabs, lobsters), centipedes

Echinodermata

Sea stars, sea urchins, sea cucumbers, sand dollars

Chordata

Vertebrates, tunicates, lancelets

Urochordata

tunicates

Cephalochordata

lancelets

Vertebrata

vertebrates

Acoelomates

Lacks a body cavity between the gut and body wall (e.g., Platyhelminthes). The space is filled with mesoderm tissue.

Pseudocoelomates

Has a body cavity (pseudocoel) partially lined by tissue derived from mesoderm—specifically between mesoderm and endoderm (e.g., Nematoda).

Coelomates

Possesses a true coelom completely lined by tissue entirely derived from mesoderm (e.g., Annelida, Arthropoda, Mollusca, Echinodermata, Chordata).

Polyp

Sessile, tubular body form with the mouth and tentacles facing upward (e.g., sea anemones, hydras, coral polyps). Typically reproduces asexually.

Medusa

Free-swimming, bell-shaped body form with the mouth and tentacles facing downward (e.g., jellyfish). Typically reproduces sexually

Evolutionary Order of Major Animal Phyla

Porifera —> Cnidaria —> Platyhelminthes —> Nematoda —> Mollusca —> Annelida —> Arthropoda —> Echinodermata —> Chordata (from early basal branching lineages to advanced deuterostomes)

Protostomes

Blastopore develops into the mouth first; cleavage is typically spiral and determinate (e.g., Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda)

Deuterostomes

Blastopore develops into the anus (mouth forms second); cleavage is radial and indeterminate (e.g., Echinodermata, Chordata)

Diploblastic

Having two primary germ layers (ectoderm and endoderm)—characteristic of Cnidaria (Porifera lack true tissue layers)

Triploblastic

Having three primary germ layers (ectoderm, mesoderm, and endoderm)—characteristic of Platyhelminthes through Chordata

Bilateral Symmetry

Can be divided into mirrored left and right halves along one plane (Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Chordata, and echinoderm larvae)

Radial Symmetry

Can be divided into symmetrical halves through multiple planes passing through a central axis (Cnidaria, adult Echinodermata).

Asymmetry

Lacks any symmetrical planes (Porifera/Sponges).

Segmented Phyla

Annelida, Arthropoda, and Chordata

Preserved Specimen Identification

Look for osculums in sponges, cnidocytes/tentacles in cnidarians, setae in earthworms, jointed appendages and exoskeletons in arthropods, and water-vascular system structures (tube feet) in echinoderms.

Flowering Plants Taxonomic Name

Angiosperms

Dermal Tissue

Outer protective covering (epidermis and periderm)

Ground Tissue

Bulk of plant tissue specialized for photosynthesis, storage, and support (parenchyma, collenchyma, sclerenchyma).

Vascular Tissue

Long-distance transport tissues

Xylem

water/minerals

Phloem

sugars/organic nutrients

Microscope/Model Parts

Cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, vascular bundles (xylem on top, phloem on bottom), lower epidermis, stomata, and guard cells.

Monocot Leaves

Parallel venation, narrow/linear shape, mesophyll often undifferentiated into palisade/spongy layers. 3 multiples

Dicot Leaves

Reticulate (net-like) venation, broad blade, clearly differentiated palisade mesophyll (upper) and spongy mesophyll (lower) 4,5 multiples

Terminal Bud

Tip of the stem for upward growth

Bud Scale Scars

Marks left where terminal bud scales dropped off previous year (used to measure age/annual growth)

Node / Internode

Node holds leaves/buds; internode is the stem space between nodes.

Axillary/Lateral Bud

Bud in leaf axil capable of forming a branch or flower.

Leaf Scar

Mark left on stem where a leaf fell off.

Lenticels

Raised pores on woody stems allowing gas exchange.

Dicot Root

Solid central core of xylem shaped like a star with phloem between the arms.

Monocot Root

Ring of alternating xylem and phloem bundles surrounding a central core of pith.

Dicot Stem

Vascular bundles arranged in a neat ring around a central pith

Monocot Stem

Vascular bundles scattered throughout the ground tissue

Epidermis

protection/absorption

Cortex

storage

Endodermis with Casparian strip

controls water entering vascular cylinder

Xylem

transports water/minerals upward

Phloem

transports sugars bidirectionally

Meristems

Regions of undifferentiated, actively dividing cells. Apical meristems drive length; lateral meristems (vascular cambium and cork cambium) drive girth

Primary Growth

Lengthening of the plant root and shoot systems (driven by apical meristems)

Secondary Growth

Thickening/widening of woody plants (driven by lateral meristems: vascular cambium adds secondary xylem/phloem; cork cambium adds protective periderm/bark).

Tree Rings

Each ring represents a year of secondary growth, formed by contrasting earlywood (large cells, fast spring growth) and latewood (small, thick-walled cells, summer/autumn growth).

Why no monocot trees

Monocots lack lateral meristems (a vascular cambium) capable of producing continuous secondary growth and wood. (Note: Trees like palms grow tall via primary thickening meristems, not true secondary woody growth).

Determining Tree Age

• Counting annual rings on a trunk cross-section or core sample (dendrochronology).

• Counting terminal bud scale scars on twigs to measure annual stem elongation increments.

• Historical records or planting dates for cultivated trees.

Porifera (Sponges)

• Tissues: None

• Symmetry: None

• Diploblastic or Triploblastic: Not applicable

• Coelom Type: Not applicable

• Protostome or Deuterostome: Not Applicable

• Key Examples: Glass sponges, bath sponges

Cnidaria (Jellyfish, Corals, Sea Anemones, Hydras)

• Tissues: Yes

• Symmetry: Radial

• Diploblastic or Triploblastic: Diploblastic

• Coelom Type: Not applicable

• Protostome or Deuterostome: Not Applicable

• Key Examples: Moon jellies, sea anemones, brain coral, Hydra

Platyhelminthes (Flatworms)

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Acoelomate

• Protostome or Deuterostome: Protostome

• Key Examples: Planarians, tapeworms, liver flukes

Mollusca (Snails, Clams, Squids, and Octopi)

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Protostome

• Key Examples: Garden snails, giant clams, cuttlefish, octopuses

Annelida (Leeches and Earthworms)

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Protostome

• Key Examples: Earthworms, leeches, polychaete tubeworms

Nematoda (roundworms)

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Pseudocoelomate

• Protostome or Deuterostome: Protostome

• Key Examples: C. elegans, pinworms, hookworms, heartworms

Anthropoda (Insects, Arachnids, Crustaceans, Myriapods)

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Protostome

• Key Examples: Honeybees, tarantulas, lobsters, centipedes

Echinodermata (Sea Stars, Sea Urchins, Sea Cucumbers)

• Tissues: Yes

• Symmetry: Bilateral as larvae, Radial as adult

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Deuterostome

• Key Examples: Starfish, sea urchins, brittle stars, sand dollars

Chordata (Sea Tunicates)

Subphylum: Urochordata

• Tissues: Yes

• Symmetry: Bilateral as larvae, Radial as adult

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Deuterostome

Chordata (Lancelets)

Subphylum: Cephalochordata

• Tissues: Yes

• Symmetry: Bilateral

• Diploblastic or Triploblastic: Triploblastic

• Coelom Type: Coelomate

• Protostome or Deuterostome: Deuterostome