Download 2.3 Taxonomy: Protozoa-Nematoda Over the next 3 labs we`re going

2.3 Taxonomy: Protozoa-Nematoda
Over the next 3 labs we’re going to examine organisms with an emphasis on the characteristics that put them into a
particular taxonomic group. The organisms that we’ll look at should be considered as representative examples and may
not be the particular organisms that show up on the practical– focus on the characteristics that define a group rather than
memorize a particular organism.
The Handout
This handout essentially contains 95% of the answers for LAB EXAM I. You will need to be able to look at a specimen
and identify it based on its taxonomy. You may be asked to identify it at any level of classification that is found on this
sheet: never a genus or species, but know the phyla, subphyla, class, subclass, infraclass, & order.
You will be responsible for examining the specimens (PREPARED SLIDES, MODELS and PRESERVED
MACROSCOPIC) that are available for each of the taxonomic groups and identify them based on the general
characteristics of their group.
You may want to draw them and make notes in your handy-dandy notebook with that in mind, i.e. with a focus on their
taxon-defining characteristics.
KINGDOM PROTISTA
These are single-celled, eukaryotic, animal-like, unicellular organisms. There are a large number of phyla, but we’ll look
at just FOUR. They are defined primarily by their mode of locomotion. They are sometimes considered acellular, since
their “bodies” are not divided into cells
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Sarcodina
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Euglenozoa
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Mastigophora
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Ciliophora
You may meet others if you take e.g. parasitology
PHYLUM SARCODINA
These are the transparent shape shifters. They move and gather food using foot-like cytoplasmic extensions called
PSEUDOPODIA
There are 2 major groups
(a)
NAKED have just a plasma membrane, and
(b)
SHELLED have exoskeleton called a TEST made of silicon or strontium compounds. TESTs have PORES
through which pseudopodia extend. TESTS can be quite ORNATE.
Naked sarcodines represented by AMEOBA. Shelled sarcodines represented by RADIOLARIANS. These were collected
from marine sediment. Just the test is left, the sarcodine is gone so you will not see the pseudopodia.
PHYLUM EUGLENOZOA
Represented by EUGLENA. Move using a FLAGELLUM, which may be hard to see unless you are observing live
specimens. They are very small (smaller than amoebas), shaped like a pointed rod and positively phototactic (moving
TOWARDS light). They have chloroplasts and are photosynthetic.
PHYLUM MASTIGOPHORA
Like Eugena, these organisms move by FLAGELLA, but most often they have multiple flagella, not one like in the case
of the Euglenozoa. They are commonly referred to as THE FLAGELLATES.
Examples are:
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TRICHONYMPHA, the mutualistic symbiotes that live in the digestive tract of termites
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DINOFLAGELLATES, marine plankton that bloom to produce RED TIDES, some contains toxins responsible
for fish kills
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TRYPANOSOMA, a blood parasite responsible for Chagas disease (sleeping disease) which is spread by Tsetse
flies. Have a long flagellum attached by an UNDULATING MEMBRANE. Slide is a blood smear so you’ll see many
RED BLOOD CELLS and occasional WHITE BLOOD CELLS; you’ll need HIGH MAGNIFICATION!
•
LEISHMANIA, teardrop-shaped blood parasites with a large nucleus and many flagella that cause serious lesions
and are transmitted by sandflies
PHYLUM CILIOPHORA
The Ciliates. Use CILIA for locomotion or to obtain food. Cilia and Flagella are structurally the same but cilia are much
shorter and often more numerous. They have distinctive nuclei (macronucleus), are often found in stagnant water and use
both sexual and asexual reproduction. Examples are PARAMECIUM, VORTICELLA (sessile, cup-shaped with a coiled
stalk) & STENTOR (cornucopia-shaped).
KINGDOM ANIMALIA
PHYLUM PORIFERA
The Sponges. These animals are multicellular, sessile, with no defined shape, porous (body permeated by water canal
system), with an INTERNAL SKELETON of SPONGIN or SPICULES. They are so different from all other animals
that they were once thought to be plants.
There are 3 CLASSES defined mostly by TYPE OF SKELETON:
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CLASS CALCAREA have spicules of CALCIUM CARBONATE with a simple shape – TUBULAR– and Small,
Simple spicules – Rod or Triradii.
See SLIDES of sections: longitudinal or cross; Look for spicules and canals in body walls. Also observe preserved or
dried specimens.
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CLASS HEXACTINELLIDA, The GLASS SPONGES, LONG, DELICATE SPICULES of silcon as in beach
sand or glass often with 6 rays and fused spicules; Collect light for symbiotic algae that provide nutrients for the sponge.
Preserved or dried specimens.
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CLASS DEMOSPONGIAE, the HORNY or TRUE SPONGES; this class contains about 80% all sponges; tend to
be LARGE with elaborate shapes: BASKET, FINGER, BATH; Skeleton of SPONGIN or SILCON; most animals are
marine with only 2 freshwater species.
PHYLUM CNIDERIA
diploblastic (no mesoderm), gelatinaceous organisms with an acellular mesoglea. Key features are:
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POLYMORPHISM
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CNIDOCYTES with NEMATOCYSTS
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RADIAL SYMMETRY
These are the first animals to have a nervous system (nerve net). Two body forms: the polyp and the medusa.
Table 1: Comparison of Cnidarian Body Forms
Body Form
Polyp
Medusa
Mouth Location
Dorsal mouth with tentacles
Ventral mouth
Lifestyle
Sessil
Mobil
Classes based on which adult body forms:
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CLASS HYDRAZOA adult form is POLYP e.g. HYDRA, but lifecycle contains both forms, polyp and medusa,
the medusa contains a velum.
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CLASS SCYPHOZOAN e.g. true jellies, adult form is MEDUSA, polyp stage is reduced or absent, all marine
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CLASS ANTHOZOA e.g. sea anemones & corals, adult form is POLYP, NO MEDUSA form, solitary or colonial
animals, thicker body wall; corals have exoskeleton (stony vs. soft); entirely marine
PHYLUM CTENOPHORA
= the COMB JELLIES, have RADIAL SYMMETRY and NO CNIDOCYTES. Look like a ball with 8 rows of COMBS
or CILIA.
PHYLUM PLATYHELMINTHES
= the FLATWORMS, TRIPLOBLASTIC, ACOELOMATE, DORSOVENTRALLY flattened organisms with well
developed organ systems and BILATERAL symmetry
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CLASS TURBELLARIA; only free-living flatworms, with an oral opening, no anus and a ciliated epidermis.
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CLASS TREMATODA; the FLUKES; internal parasites, covered by a hardened cuticle with 2 suckers for
attachment.
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CLASS CESTODA; the TAPEWORMS; body divided into sections (proglottids), with a thick tegument (skin), a
specialized scolex with hooks and/or suckers and no mouth or digestive tract.
PHYLUM NEMATODA
= the ROUNDWORMS, animals with an elongate, cylindrical body covered by a tough, flexible cuticle, have a pharynx
and specialized excretory system, many are parasitic (e.g. Ascaris lumbricoides, Trichinella spiralis), some free-living
(e.g. Caenorhabditis elegans)
PHYLUM ROTIFERA
Common and abundant freshwater animals, covered by a syncytical epidermis with a cuticle, contain a specialized ciliary
feeding and locomotion organ = CORONA (wheel organ), internal grinding organ = MASTAX, many types have an
adhesive foot
PHYLUM ACATHOCEPHALA
= the spiny-headed worms, internal parasites in freshwater fish, contain a hook-bearing proboscis for attachment,
digestive tract is absent
PHYLUM GASTROTRICHA
= “stomach hairs”, most less than 1 mm long, superficial resemblance to rotifers but without the corona, contain 2 or more
adhesive tubes, cuticle often forming plates and spines, hermaphroditic animals.