Marine Invertebrates and Taxonomy

A comprehensive set of practice flashcards covering marine invertebrate taxonomy, specific phyla characteristics (Porifera, Cnidaria, Ctenophora, Mollusca, Arthropoda, Echinodermata), homeostasis, and extreme environment adaptations.

What structure do Choanoflagellates use for travel and what is the function of their membranous collar?

They use a whip-like flagellum for travel and a membranous collar to filter bacteria and eat.

How do Amoebas move and capture food?

They use pseudopods (cytoplasmic flow) for movement and phagocytosis to engulf food.

Which 6 phyla of Invertebrates are listed in the study guide?

Phylum Porifera, Phylum Cnidaria, Phylum Ctenophora, Phylum Mollusca, Phylum Arthropoda, and Phylum Echinodermata.

What are spicules in the skeleton of a sponge?

Internal "bricks" or rods made of silica or calcium carbonate that provide rigid support.

What is the role of spongin in Phylum Porifera?

It is a modified collagen protein acting as "mortar" or fibers to hold spicules together.

What is the function of Choanocytes in sponges?

They are "collar cells" that use flagella to create water currents and trap food particles.

How does sexual reproduction occur in Phylum Porifera?

Sperm is released through the osculum and trapped by the choanocytes of another sponge; the resulting zygote develops into a motile larva that swims using cilia before settling.

What are the three main classes of sponges?

Calcareous (chalky), Glass (silica), and Demosponges (which make up $80\%$ of all sponges).

What volume of water can a single kilogram of sponge filter in one day?

$24,000$ liters.

What type of symmetry do organisms in Phylum Cnidaria possess?

Radial symmetry.

What is the mesoglea in Cnidarians?

An extracellular matrix functioning as a hydrostatic skeleton.

What specialized cells do Cnidarians use for defense and feeding?

Nematocysts (stinging cells).

Distinguish between the dominant life stages of Class Hydrozoa, Scyphozoa, and Anthozoa.

In Hydrozoa the polyp stage is dominant; in Scyphozoa the medusa form is dominant; in Anthozoa only the polyp form exists.

What structure do Ctenophores use for locomotion?

They use $8$ rows of cilia called "ctenes".

How do Ctenophores capture prey without stinging cells?

They use sticky cells called colloblasts.

What causes the "rainbow" colors seen on the ctenes of comb jellies?

Light scattering (refraction) off the moving cilia.

What is the function of the radula in Phylum Mollusca?

It is a barbed, rasping tongue used for feeding (though it is absent in bivalves).

Compare the limbs of a squid versus an octopod.

A squid has $10$ limbs ($8$ arms + $2$ tentacles) while an octopus has $8$ arms and no tentacles.

What is the composition of the Arthropod exoskeleton?

A hard external skeleton made of chitin and protein.

What is ecdysis in the context of Phylum Arthropoda?

The process of molting, or shedding the hard exoskeleton in order to grow.

Which phylum is the largest in the animal kingdom, and what percentage of all animals does it represent?

Phylum Arthropoda; it represents $80\%$ of all animals.

What is the unique symmetry transition found in Phylum Echinodermata?

Adults have pentamerous radial symmetry, while larvae have bilateral symmetry.

Why are Echinoderms considered more closely related to chordates than other invertebrates?

They are deuterostomes, sharing very similar zygote and cell development patterns with chordates.

What is the function of the water vascular system in Echinoderms?

A network of water-filled canals used for movement, gas exchange, and feeding.

How does a cold ambient temperature affect the heart rate of a poikilotherm?

Biochemical reactions slow down, requiring less $O_2$, which causes the heart rate to slow down.

How does the metabolic reaction to cold in a homeotherm differ from a poikilotherm?

In a homeotherm, the hypothalamus signals cells to burn sugar for heat, causing the heart rate to increase to deliver blood to active cells.

What adaptation do deep-sea fish use to deal with crushing pressure in their swim bladders?

Some put more oxygen into their swim bladders, while others use fats or oils instead of gas because liquids and solids do not compress like gas.

What wavelength of light do most bioluminescent deep-sea organisms use and why?

Blue-green light, because it has a short wavelength that travels furthest in the ocean.

How do organisms survive in hydrothermal vent ecosystems without sunlight?

Bacteria (extremophiles) use chemosynthesis to produce sugar from chemicals like hydrogen sulfide, often living symbiotically inside animals like giant tube worms.