Zoology 12
Terms
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- micromeres
- The smallest size class of blastomeres in a cleaving embryo when the blastomeres differ in size from one another.
- brackish
- Water having salinity intermediate between freshwater and seawater, ranging from .5 to 30 parts per thousand.
- sclerocytes
- An amebocyte in sponges that secretes spicules.
- inversion
- A turning inward or inside out, as in embryogenesis of sponges; also, reversal in order of genes or reversal of a chromosome segment.
- spicules
- One of the minute calcareous or siliceous skeletal bodies found in sponges, radiolarians, soft corals, and sea cucumbers.
- prosopyles
- Connections between the incurrent and radial canals in some sponges.
- monoecious
- Having both male and female gonads in the same organism; hermaphroditic.
- choanocyte
- One of the flagellated collar cells that line cavities and canals of sponges.
- apopyles
- In sponges, opening of the radial canal into the spongecoel.
- lophocytes
- Type of sponge amebocyte that secretes bundles of fibrils.
- trabecular reticulum
- A bilayered, syncytial tissue forming the main body structure of hexactinellid sponges (phylum Porifera).
- myocytes
- Contractile cell (pinacocyte) in sponges.
- asconoid
- Simplest form of sponges, with canals leading directly from the outside to the interior
- collar bodies
- Extensions of choanoblasts bearing flagellated collars in hexactinellid sponges.
- syconoid
- the choanocytes lie in canals
- osculum
- Excurrent opening in a sponge.
- micropyle
- The small opening through which cells emerge from a gemmule (phylum Porifera).
- archaeocytes
- Ameboid cells of varied function in sponges.
- intracellular
- Occurring within a body cell or within body cells.
- spongocoel
- Central cavity in sponges.
- gemmules
- Asexual, cystalike reproductive unit in freshwater sponges; formed in summer or autumn and capable of over wintering.
- pinocytosis
- Fluid acquisition by a cell in which specific receptors bind ions/molecules present on plasma membranes, which are invaginated and pinch off to form small vesicles.
- spongocytes
- A cell in sponges that secretes spongin.
- collencytes
- A type of cell in sponges that is star-shaped and apparently contractile.
- spongin
- Fibrous, collagenous material forming the skeletal network of demosponges.
- metazoans
- Multicellular animals.
- dermal ostia
- Incurrent pores in a sponge
- phagocytosis
- The engulfment of a particle by a phagocyte or a protozoan.
- monophyletic
- The condition that a taxon or other group of organisms contains the most recent common ancestor of the group and all of its descendants; contrasts with polyphyly and paraphyly.
- suspension feeding
- Aquatic organisms that collect suspended food particles from the surrounding water; particles may be filtered or taken by other methods.
- macromeres
- The largest size class of blastomeres in a cleaving embryo when the blastomeres differ in size from one another.
- leuconoid
- A type of canal system in sponges where choanocytes reside in chambers.
- parenchymula
- Flagellated, solid-bodied larva of some sponges.
- choanoblasts
- One of several cellular elements within the syncytial tissue of a hexactinellid sponge; choanoblasts bear flagellated extensions called collar bodies.
- pinacoderm
- The layer of pinacocytes in sponges.
- pinacocyte
- Flattened cells composing dermal epithelium in sponges.
- mesenchyme
- Embryonic connective tissue; irregular or amebocytic cells often embedded in gelatinous matrix.
- polyphyly
- The condition that a taxon or other group of organisms does not contain the most recent common ancestor of all members of the group, implying that it has multiple evolutionary origins; such groups are not valid as formal taxa and are recognized as such only through error.
- somatic embryogenesis
- somatic refers to the body, for example, somatic cells in contrast to germ cells.
- mesohyl
- Gelatinous matrix surrounding sponge cells; mesoglea, mesenchyme.
- radial canals
- Canals along the ambulacra radiation from the ring canal of echinoderms; also choanocyte-lined canals in syconoid sponges.