Invertebrate Zoology - Daily

What does the term “bauplan” mean?

It means the structural body plan or architecture of an animal that enables its functions.

What is one constraint faced by marine, freshwater, and terrestrial animals?

Marine: stable isotonic environment; Freshwater: constant water influx/osmoregulation; Terrestrial: water loss/UV/desiccation risk.

Why do small animals rely mainly on diffusion?

They have a high surface-area-to-volume ratio; large animals need bulk transport systems.

What are the main symmetry types in animals?

Asymmetry, radial, biradial, quadriradial, pentaradial, bilateral.

What does oral vs aboral mean?

Oral = side with the mouth; Aboral = side opposite the mouth.

What does anterior vs posterior mean?

Anterior = head/front end; Posterior = tail/back end.

Explain homology vs analogy with an example.

Homology = similarity from common ancestry (bat wing vs dog limb); Analogy = similarity from convergent function (bird vs insect wings).

What is cephalization?

Concentration of sensory and feeding structures at the front (anterior).

Why is folding or coiling important in body plans?

It increases surface area for exchange and absorption.

What are the five mammalian tissue systems?

Epithelium, connective, muscle, nervous, and blood.

What is the late exam/quiz policy in this course?

No late exams; one quiz make-up allowed; otherwise zero.

What are the grading thresholds for A, B, C, D?

A ≥ 90, B ≥ 80, C ≥ 65, D ≥ 55.

How do you align the microscope condenser properly?

Focus condenser to slide, close diaphragm, center image with screws, then open just beyond field edge.

When do you use the convex lens on the microscope?

At 4× objective only.

What two mistakes commonly blur microscope images?

Over-opening the diaphragm or leaving condenser mis-centered.

What five items must every lab drawing include?

Taxon name, labeled structures, magnification/field size, date/name, and a scale bar.

How should drawings be oriented?

Anterior/dorsal side toward the upper left.

Why use single-line outlines and cross-hatching in drawings?

They ensure clarity and avoid muddy images.

What kind of paper and units are required for lab drawings?

Biology paper; metric units.

Why must genus and species be included on lab drawings?

For unambiguous identification and grading accuracy.

What are the three layers in a sponge body?

Pinacoderm, choanocyte layer, and mesohyl.

What is the role of porocytes and pinacocytes?

Porocytes form incurrent pores; pinacocytes cover the surface like epithelium.

What is the function of choanocytes?

Flagellated collar cells that create water flow and capture food particles.

What is the function of archaeocytes?

They are totipotent amoeboid cells that phagocytose, transport, and differentiate.

What do sclerocytes do?

They secrete spicules.

How do the asconoid, syconoid, and leuconoid body types differ?

Asconoid = simple tube; Syconoid = folded walls; Leuconoid = chambers, most efficient for filtration.

Why is the leuconoid type most efficient?

It maximizes surface area for filtering water.

What are sponge spicules made of?

Silica or calcium carbonate.

What does “hexactine” mean in spicules?

Six-rayed spicule found in Hexactinellida.

What protein makes up spongin and what is its function?

Collagen-like protein that adds flexibility and support.

What is the difference between the osculum and ostia?

Osculum = excurrent opening; Ostia = small incurrent pores.

What class of sponges includes ~90% of species?

Demospongiae, which are leuconoid and have siliceous spicules with spongin.

Give an example of a carnivorous sponge.

Chondrocladia, which has harpoon-like spicules.

Why are choanocyte beats not synchronized?

To maintain steady microcurrents and avoid flow interference.

What happens to sponge cells in Ca²⁺/Mg²⁺-free seawater?

They stay dissociated because ions are needed for adhesion proteins.

What does adding the aggregation factor to sponge cells cause?

Cells re-aggregate and sort species-specifically.

What are the three dish conditions tested in the sponge lab?

Ca²⁺/Mg²⁺-free seawater, normal seawater, and normal seawater with protein factor.

Which sponge class has hexactine spicules?

Hexactinellida.

Where are gemmules found and in what sponges?

In freshwater sponges like Spongilla.

Which cells make spicules?

Sclerocytes.

Why rinse cells several times in ion-free seawater before dissociation?

To remove Ca²⁺/Mg²⁺ and disrupt adhesion proteins.

What does the no-protein control dish show?

Baseline aggregation in normal seawater without the factor.

What happens if Ca²⁺/Mg²⁺ are added back to ion-free seawater?

Adhesion ability is restored.

What are the two germ layers of cnidarians?

Ectoderm and endoderm.

What lies between the two layers of cnidarians?

Mesoglea, a gelatinous matrix.

How do cnidarians move without mesodermal muscles?

Using epitheliomuscular cells in the epidermis.

What is unique about the Anthozoa life cycle?

They have no medusa stage, only polyps.

What is a siphonoglyph and its function?

A ciliated groove that drives water into the gastrovascular cavity.

How do Hexacorallia and Octocorallia differ?

Hexacorallia: multiples of six tentacles/septa; Octocorallia: eight pinnate tentacles and mesenteries.

Which anthozoan group builds stony reefs?

Hexacorallia (scleractinian corals).

What are anthozoan symbionts and why are they important?

Symbiodinium algae; they provide nutrients and require light.

What are spirocysts and acrorhagi?

Spirocysts = sticky threads for adhesion/capture; Acrorhagi = specialized fighting tentacles.

How do anthozoans reproduce?

Release gametes → planula larva → polyp; also asexual budding or pedal disc fission.

Give an example of a local anemone.

Anthopleura elegantissima, found on the California coast.

Give an example of an octocoral.

Gorgonia (sea fan).

What does pedal disc budding accomplish?

Asexual expansion of the colony.

Which anthozoan subclass has 8 pinnate tentacles?

Octocorallia.

How do Xenia polyps obtain food?

They photosynthesize using their symbionts only.

Name two anthozoan genera you may identify in lab.

Cladiella, Aiptasia, Metridium, Montipora.

What structures are visible in a Metridium cross section?

Septa and the pharynx (plus mesenteries).

What structure inflates soft corals?

The coelenteron filled with water (hydrostatic skeleton).

Why does turbid water harm corals?

It reduces light available for Symbiodinium photosynthesis.

Give an example of a local octocoral.

Clavularia from California.

What is Balanophyllia elegans and its trait?

A solitary stony coral species.

Give one coral predator and one coral grazer.

Acanthaster planci (crown-of-thorns starfish); Chlorurus sordidus (parrotfish).

What is the typical life cycle of scyphozoan jellyfish?

Planula → scyphistoma → strobila → ephyra → medusa.

What are two diagnostic features of a scyphozoan medusa?

Four gastric pouches and lappets or oral arms.

What is a planula larva?

A ciliated larva that develops into the polyp’s epidermis and gastrodermis.

How are hydrozoan colonies polymorphic?

Gastrozooids handle feeding; Gonozooids produce medusae.

What feature is characteristic of hydrozoan medusae?

They have a velum and ectodermal gonads.

What is unique about Hydra among hydrozoans?

It is freshwater and lacks a medusa stage.

What is an example of a siphonophore?

Physalia (Portuguese man-o’-war).

From what tissue are hydrozoan gonads derived?

They are ectodermal.

What are the perisarc and theca in hydrozoans?

Perisarc = protective covering; Theca = sheath around hydranth.

Give an example of a hydrozoan with a CaCO₃ skeleton.

Stylaster (Allopora).

What does the strobila stage of Aurelia look like?

A stack of disc-like ephyrae buds.

Which scyphozoan has symbionts and rests upside-down?

Cassiopea (the upside-down jellyfish).