Principles II Lab 1

D. Wasserman

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Amoeba proteus

Euglenozoans

Paramecium

Volvox

Poriferans (sponges)

Cnidarians

Platyhelminthes

Cestodans (tapeworms)

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Today

• Use microscope and dissecting scope to look at a assortment of living single and multicellular animals
• Protists
• Paramecium, Euglena, Volvox, Amoeba, diatom
• We focus on organelles that we can see. If it’s not addressed in manual, ppt., or lecture, you aren’t expected to study it. If it cannot be identified in lab, you will not be expected to identify it on an exam or quiz. If you do not see it in lab, it should not be in results section of a lab report.

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• Use microscope to look at pre-prepared slides
• Poriferan
• Obelia (jellyfish)
• Diatoms

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• Look at whole, preserved specimens
• Poriferan, “loofa” and calcareous
• Cnidarians- live anemone and slides

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Characteristics

Know the structures and organisms we address in lab, lecture or ppt. as well as their identifying characteristics.

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You may be expected to recognize the same animals or groups in different formats than what you saw in lab, based on their diagnostic features.

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You should know the diagnostic characteristics as well as the organisms.

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Difference between “protist” and “Protista”

• Protista is taxonomic nomenclature
• a proper noun
• first letter is capitalized
• always singular

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• Protist is descriptive
• vernacular
• can pluralize
• cap. only if at beginning of sentence

Same goes for “protazoan” and “Protazoa”

Animals

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All animals

• lack cell wall (they do have membranes)
• have at least one motile life stage
• ex: mature sponges, which are sedentary, have a free-swimming larval stage

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Energy synthesis methods

• Autotrophy: from chemicals or sunlight
• Heterotrophy: from animals and plants

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Some single-celled animals, such as euglenoids, are non-obligate autotrophs. They’re predominantly heterotrophic but have autotrophic capability.

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Euglena (a protist)

Euglena is a genus. Euglenozoan is a category.

• An non-obligate, autotrophic, single-celled eukaryote
• Plant-like
• Eats biomatter and contains chloroplasts that synthesize energy from sunlight.
• All have a flagellum and pellicle

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Live Euglena sp. at 400x magnification.

What are these features?

Longitudinal binary fission

• Not the same thing as mitosis here because there is no spindle formation. It’s simply the splitting of a cell.
• Common in unicellular organisms such as species of Euglena

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How euglenozoans reproduce

• Plant-like protist
• An fully autotrophic, colonial eukaryote
• Individual cells are aggregated in colonies of up to 50,000 cells.
• Volvox cells can’t survive independently.
• Flagellates
• Eyespots help them move toward light.

Volvox

Note: Volvox is a genus so it must be italicized

Amoeba proteus

• A simple, slow-moving protist that engulfs food items with ephemeral bodily extensions (pseudopodia).
• Nutrients are acquired via direct absorption.
• They reproduce asexually, via binary fission.
• Feeds on bacteria and smaller protists

Study the behavior during class. Also keep in mind that it has a nucleus and cell membrane etc. Look for the characteristics of a eukaryotic cell.

Pseudopodia forming as cytoplasm moves against inner cell membrane, distending it. Pseudopodia enable movement and the engulfing of food items.

Note: Amoeboid cells occur not only in the animal kingdom, but also in fungi, algae and plants.

Diatoms

• Highly geometric single celled alga
• Component of diatomaceous earth which has industrial application
• Most are planktonic (marine)
• Presence of a silica shell is shared, derived characteristic
• Contains chloroplasts that produce approx. 20% of the planet’s oxygen

Diatom in gliding motion

An assortment of diatom species

Today we are looking at pre-prepared slides. Look for the features of eukaryotes and learn to recognize them as diatoms.

A culture of a Paramecium sp. feeding on brown algae

Alveolata

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• A free-swimming, freshwater ciliate.
• Eats biomatter exclusively (is heterotrophic).

Paramecium sp.

• Rotifer filter feeding. Vibrating cilia create current that draws food into the mastax of the body cavity.

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• We will look at these animals next week. It’s microscopic but it is not a protist because it is multicellular.

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• It is also a pseudocoelomate. All of today’s animals are acoelomates.

Next week

Diagram showing the three general types of body plans in animals.

Porifera (sponges)

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Note: “Porifera” is a phylum. “Poriferan” is a descriptive term for these animals.

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Etymology: “Porifera”, “pore-bearing”

Amoebocytes (aka choanocytes) are collar cells that create a current which is vital to feeding, oxygenation and waste removal in sponges.

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Choanoflagellates (right) are free-swimming protists with collars of microvilli and flagella. -------------------------->

• Popular hypothesis: choanocytes were free-swimming protists that began living in sponge walls and a symbiotic relationship developed.

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“Presence of choanocytes” is a shared derived characteristic of Porifera. It appeared in the ancestral sponge lineage after the lineage of Porifera gained evolutionary independence on the the tree of life.

Cladogram depicting evolutionary relationships among the four classes of sponges.

Presence of spicules is a shared, derived characteristic in sponges. Spicule shape can be used to identify taxonomic groups.

Produced by Andrea Murillo-Rincon, Dr. Alexander Klimovich

Hydra sp. expanding and contracting

Today, we will study:

1-2) live hydrozoans (Hydra)

3-4) pre-prepared slides of cnidocytes and Obelia

Cnidaria: hydrozoans, jellyfishes, anemone, corals.

• Some hydrozoans have symbiotic algae living between their tissue cells, making them appear green.
• Radially symmetric

Hydra sp. that is host to algal symbionts.

Is this a coelomate? It has a gastrovascular cavity. It opens to the environment and there is direct nutrient and oxygen absorption to tissue cells.

Hydra sp., whole mount. A-tentacle, B-hypostome, C-body column, D-basal disc

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Etymology: “Cnidaria”, “knide” means nettle (Greek)

The presence of cnidocytes is a shared derived characteristic of cnidarians.

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Location

Hydroid colony at 40x. Identify these features on your pre-prepared slide. Learn to distinguish a breeding bud from a feeding bud.

Platyhelminthes (flatworms)

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Note: Platyhelminthes is a phylum. Planarian is a type of organism within that phylum.

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We are studying live planarians and a pre-prepared slide of a stained Dugesia

Planaria sp.

• Regenerative capabilities
• Mostly scavengers
• Have three germ layers but lack a body cavity (acoelomates)
• Moves via beating cilia on ventral dermis

Study the behavior of your live specimen. Attempt to feed it. On the slide of Dugesia, take note of:

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• eyespots
• auricle
• ganglia
• protonephridia
• pharynx

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Eyespots: areas of un-pigmented cells with a cluster of photosensitive cells in the center.

Cestodes (tapeworm)

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Note: Cestodes is a phylum. It is also a member of Platyhelminthes! It is a flatworm.

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We are studying a pre-prepared slide of the segments which contain reproductive anatomy.

• Endoparasitic flatworm
• All have a scolex that anchors tapeworm to digestive tract of host. Contains hooks and suckers.
• No mouth or digestive organs. Direct nutrient absorption from host.

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The anatomy of a tapeworm, based off of Taenia solium specimen.This is the species in our pre-prepared slides.

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