Animal Diversity Exam 2 - Taxonomy, Common Names, and Body Plans

Describe the germ layers of the taxa on this exam.

ALL taxa on this exam are triploblastic.

Describe the body cavities of the taxa on this exam.

Acoelomates: Phyla Platyhelmenthes (parenchyma) and Gastrotricha (debated)

Pseudocoelomates: Rotifera

Coelomates: Phyla Ectoprocta, Brachiopoda, Nemertea (rhynchocoel), Annelida, and Mollusca

Describe the symmetry of the taxa on this exam.

ALL taxa on this exam have bilateral symmetry, which indicates at least some level of cephalization.

Describe the embryonic development of the taxa on this exam.

ALL taxa on this exam:

• Are protostomes

• Have spriral cleavage

• Have mosaic embryos

  • Are schizocoelous (EXCEPT for Platyhelminthes and Gastrotricha, whice are neither schozocoelous nor enterocoelous due to being acoelomates).

Describe the skeletal structure(s) of the taxa on this exam.

• Hydrostatic: Platyhelminthes, Rotifera, Gastrotricha, Nemertea, Annelida, and some Molluscs that have lost their shells (ex. slugs, octopus, cuttlefish, squids, etc.)

• Exoskeleton/shell: Ectoprocta, Brachiopoda, and Molluscs that still retain their shells (chitons, bivalves, some snails, nautilus, etc.)

Describe the segmentation of the taxa on this exam.

No taxa on this exam are truly segmented BUT Phylum Annelida.

Phylum Platyhelminthes:

Flatworms (flukes, tapeworms, and planarians)

Class Cestoda:

Tapeworms

Class Monogenea:

Parasitic flatworms/flukes

Class Turbellaria:

Planarians

Class Trematoda:

Trematodes (flukes)

What phyla (covered in this class) make up the superphylum Lophotrochozoa?

1. Gastrotricha

2. Rotifera

3. Ectoprocta

4. Brachiopoda

5. Nemertia

6. Annelida

7. Mollusca

Phylum Gastrotricha:

Gastrotrichs (“hairybellies”)

Phylum Rotifera:

Rotifers and Acanthocephalans

Phylum Ectoprocta:

Bryozoans (“moss animals“)

Phylum Brachiopoda:

Brachiopods (“lamp shells”)

What 2 classes are in Phylum Brachiopoda and what feature distinguishes the two?

Class Inarticulata: valves are not hinged

Class Articulata: valves are hinged via tooth-and-socket hinge

Phylum Nemertea:

Ribbon worms

Phylum Annelida:

Segmented roundworms (polychaetes, oligochaetes, leeches, and allies)

Family Chaetopteridae:

Parchment worms (under Phylum Annelida, awaiting further placement)

Class Errantia:

Marine polychaetes

Class Sedentaria:

Sister class to Errantia; contains many polychaetes, oligochaetes, and leeches

What two families (that are covered) are within order Clitellata?

Family Lumbricidae (earthworms) and Hirudinidae (leeches)

Family Lumbricidae:

Earthworms

Family Hirudinidae:

Leeches

What 5 classes (that are covered) are in Phylum Mollusca?

1. Class Polyplacophora — chitons

2. Class Gastropoda — snails, slugs, limpets, and sea hares

3. Class Bivalvia — bivalves (clams, oysters, mussels, etc.)

4. Class Cephalopoda — squids, octopus, cuttlefish, and nautilus

5. Class Scaphopoda — tusk shells

Class Polyplacophora:

Chitons

Class Gastropoda:

Snails, slugs, and allies

What three subclasses make up Class Gastropoda?

1. Subclass Prosobranchia

2. Subclass Opisthobranchia

3. Subclass Pulmonata

Subclass Opisthobranchia:

Nudibranchs (sea slugs), sea hares, and sea butterflies

Class Bivalvia:

Clams, oysters, mussels, scallops, and others

What 2 subclasses and 3 orders (that are covered) are under Class Cephalopoda?

1. Subclass Coleoidea

   1. Order Teuthoidea - squids

   2. Order Sepioidea - cuttlefish

   3. Order Octopoda - octopus

2. Subclass Nautilodea - nautilus

Class Scaphopoda:

Tusk shells

T/F: animals in Phylum Platyhelminthes have a circulatory, respiratory, and skeletal system.

False; Platyhelminths lack all of these systems.

Platyhelminthes symmetry:

Bilateral

Platyhelmithes germ layers:

Triploblasts (3 germ layers)

From what germ layer(s) do the muscles derive from in platyhelminths?

The mesoderm

Platyhelminthes body cavity:

Acoelomate; spaces between organs filled with parenchyma

Platyhelminths are flattened _____. How does this modification benefit platyhelminths?

Dorsoventrally. Increases the relative surface area and decreases the distance from their body surface to their inner organs; important since they rely on their surface for diffusion, osmoregulation, and waste transfer

Are platyhelminths cephalized?

Yes; sense organs and ganglia concentrated on anterior end (simple brain)

Describe the nervous system of Phylum Platyhelminthes.

Some have a simple nerve net, but most have a more complex “ladder-like” system:

• Central cerebral ganglia coordinate impulses, 1-5 lateral nerve cord pairs carry information longitudinally, and smaller transverse nerves branch off and connect the lateral nerve cords

• Sense organs concentrated in auricles (head protrusions)

Describe the digestive system of Phylum Platyhelminthes.

• Incomplete; typically composed of a mouth, a muscular pharynx, and a branched intestine (except Cestodes, which don’t have a digestive system and instead use the digestive systems of their host)

• Branched intestines: Trematodes and Monogenans have 2 branches, Turbellarians have 3+

• Both extracellular (enzymes) and intracellular (phagocytosis) digestion occurs

• Any undigested food is expelled out of the mouth

Describe the excretory system of Phylum Platyhelminthes.

Located ventrally; osmoregulation done by protonephridia/flame cells

Describe a protonephridia

Made up of a flame cell, tube cell, and a tubule connecting them; tubules empty out through the nephridiopores on the surface of the body. Flame cells use flagella to create a vacuum, which draws in water through a filter and propels it into the tubule; any large molecules are retained by a filter.

Name the sense organs that can exist in platyhelmiths.

• Ocelli (light)

• Statocysts (balance)

  • Chemoreceptors

• Tactile sensors (touch)

• Rheoreceptors (direction)

T/F: Class Turbellaria is capable of asexual and sexual reproduction.

True; asexual through regeneration and mitotic reproduction in some species