Aquatic Organisms Lab Review

Comprehensive vocabulary flashcards covering aquatic decomposers, plant-like protists (green algae, diatoms), animal-like protists (protozoans), sponges (Porifera), and crayfish anatomy.

Decomposers (Aquatic)

Organisms such as bacteria and fungi (and additionally crustaceans and mollusks) that recycle nonliving organic matter and return materials to the aquatic environment.

Algae

Plant-like protists that are photoautotrophs capable of conducting photosynthesis, including unicellular forms such as diatoms as well as multicellular forms.

Green Algae

A group containing unicellular and multicellular species that are mostly aquatic, though some species live on tree trunks and buildings; not all members appear green.

Volvox sp.

A colonial freshwater green alga consisting of a single parent organism containing several internal daughter colonies.

Spirogyra crassa

A filamentous freshwater green alga known as 'water-silk' that floats on the surface of quiet ponds and ditches and features spiral-shaped chloroplasts.

Conjugation (Spirogyra crassa)

A sexual reproduction process where a conjugation tube develops between adjacent filaments, allowing protoplasts from one tube to migrate and fuse with waiting protoplasts in the other filament.

Zygote (Spirogyra crassa)

A thick-walled diploid structure resulting from conjugation that undergoes meiosis to form $4$ haploid cells, of which only one survives to germinate into a new filament.

Diatoms

Unicellular photosynthetic algae occurring in marine and freshwater environments that possess a two-halved silica ($\text{SiO}_2$) shell (test) in various geometric shapes.

Test (Diatom)

The rigid silica ($\text{SiO}_2$) external shell of a diatom composed of two overlapping halves, commonly preserved in the fossil record and used in filters, polishes, and paints.

Raphe

A longitudinal groove or slit located along the valve of certain diatom shells involved in motility and structure.

Protozoa

Animal-like, heterotrophic protists classified into groups based on their mode of locomotion: Zooflagellates, Amoebas, Ciliates, and Apicomplexans.

Zooflagellates

Heterotrophic animal-like protists that move using one or two flagella.

Amoebas (Amoeboids)

Aquatic protozoans found in freshwater and marine habitats that move and feed using pseudopodia and reproduce asexually by fission.

Ciliates

A group of animal-like protists that move and feed by the coordinated beating of hair-like projections called cilia.

Apicomplexans

Parasitic protozoans that feed on the fluid and body cells of host organisms.

Pseudopodia

Temporary cytoplasmic extensions used by amoeboid protists for cell motility and engulfing food particles.

Phagocytosis (Amoeba)

The process by which an amoeba engulfs food particles using pseudopodia to form an intracellular food vacuole, which then fuses with a lysosome for digestion.

Contractile Vacuole

A specialized organelle within amoebas and other freshwater protists responsible for osmoregulation by expelling excess water.

Ectoplasm

The clear, non-granular outer layer of cytoplasm located directly beneath the plasma membrane in an amoeba.

Endoplasm

The granular inner region of the cytoplasm in an amoeba containing major cell organelles and vacuoles.

Foraminiferans

Marine amoeboid protists with porous shells composed of calcium carbonate through which pseudopodia extend; dead specimens form seafloor sediments and limestone deposits.

Radiolarians

Marine protists with rigid endoskeletons made of silicon dioxide ($\text{SiO}_2$) and thin, stiff pseudopods whose skeletal remains form deep-sea sediments used to date rock strata.

Phylum Porifera

The simplest multicellular animals (sponges) lacking true tissues and organs, characterized by a porous body wall with water canals and filter-feeding behavior.

Ostia

Tiny incurrent pores on the sponge body surface that allow water containing food particles and oxygen to enter the canal system.

Osculum

A large excurrent opening at the top of a sponge through which filtered water is expelled from the spongocoel.

Spongocoel

The central internal cavity or chamber of a sponge lined with flagellated collar cells.

Choanocytes

Flagellated collar cells lining internal sponge cavities that generate water currents and trap suspended food particles.

Sponge Canal Systems (Asconoid, Syconoid, Leuconoid)

The three structural body grades of sponges ranging from simple unfolded cylindrical walls (asconoid) to folded radial canals (syconoid) to complex, branched chamber networks (leuconoid).

Gemmule

An internal asexual reproductive bud produced by freshwater and some marine sponges, composed of archaeocytes enclosed by an inner membrane and protective spicules with a micropyle opening.

Spongin

A fibrous collagen protein that forms the flexible skeletal support network in many sponges.

Spicules

Microscopic mineral structures composed of calcium carbonate or silica that provide structural support and defense in sponges, essential for sponge classification.

Megascleres and Microscleres

The two primary size categories of sponge spicules: megascleres include large structural types (monaxons, triaxons, tetraxons, polyaxons), while microscleres are smaller packing elements.

Scypha (Grantia) sp.

A small syconoid marine sponge belonging to the class Calcarea, characterized by needle-like calcium carbonate spicules around its osculum.

Cephalothorax (Crayfish)

The fused head and thoracic region of a decapod crustacean, covered dorsally by the hard carapace.

Cheliped

The first pair of walking legs (pereopods) in a crayfish, modified into enlarged pincers (chelae) for defense and prey capture.

Pereopods

The five pairs of thoracic walking legs in a crayfish used for locomotion and food manipulation.

Pleopods (Swimmerets)

Paired abdominal appendages in crayfish used for swimming and reproductive functions such as holding developing eggs or transferring sperm.

Copulatory Swimmerets

The modified, rigid first and second pairs of swimmerets found on male crayfish, used to transfer sperm to the female during mating.

Seminal Receptacle (Crayfish)

An external depression on the mid-ventral surface of a female crayfish between the walking legs where sperm is deposited and stored.

Green Gland (Antennal Gland)

Paired excretory organs located near the base of the antennae inside the crayfish head that filter body fluids and eliminate metabolic wastes.

Gastric Mill

Chitinous teeth located within the cardiac chamber of the crayfish stomach used for grinding ingested food mechanically.