Biology of Invertebrates - Sponges

Choanoflagellates

Solitary or colonial aquatic eukaryotes, with each cell having a flagellum surrounded by a collar of microvilli

Microvilli

Collects particles like bacteria

Sponges

Simple bodies composed of aggregates of several cell types held together by extracellular matrix

Placozoans

Have small nuclear genome and the largest mitrochondrial genome in the animal kingdom

Choanocytes

Used to move water to bring food and oxygen while removing wastes

Dermal cells

Many sponge species are brightly colored because of pigments in

Spongin

Collagen type in sponges

Mesohyl

Gelatinous protein matrix, which contains ameobocytes of various types and skeletal elements in sponges

Calcarea

Class of sponge with calcium carbonate spicules with one, three, or four rays

Hexactinellids

Class of sponge, glass sponges with six rayed siliceous spicules

Demospongiae

Class of sponge with siliceous spicules around axial filament, sponging fibers, or both

Homoscleromorpha

Formed to contain sponges without a skeleton or with siliceous spicules without an axial filament

Pinacoderm

In sponges, there are body openings that consist of small incurrent pores “dermal ostia” in the outer layer of cells

Internal canal systems

Sponges feed by collecting suspended particles from the water through

Microvilli

In the collar trap and phagocytize food particles that pass by

Phagocytosis

The smallest particles are taken into choanocytes by

Pinocytosis

Protein molecules may be taken in by

Pinacocyte - archaeocyte

Cell type that facilitate feeding

Asconoid

Small and tube-shaped to allow water to flow directly across cell so no “dead space”

Spongocoel

In asconoids, the choanocytes are in a large internal chamber called

Osculum

In asconoids, water is expelled through

Sycanoid

Body wall is folded outwards with choanocyte-lined radial canals that empty into spongocoel

Prosopyles

In syconoids, water enters through dermal ostia and move into tiny openings called

Apopyles

In syconoids, food is ingested by choanocytes and used water is pumped through internal pores called

Epithelial cells

In syconoid, spongocoel is lined with

Leuconoids

Most complex and larger, for more food collecting regions, these regions have choanocytes lining in small chambers that effectively filter all water present

Mesohyl

Sponge cells are arranged in a gelatinous extracellular matrix called

Contractile Vacuoles

In archeocytes and choanocyte, respiration and excertion via diffusion and water regulation is done via

Collar

Consists of microvilli connected to each other by fine microfibirils

Choanocytes

Oval cells with one end embedded in mesohyl and exposed end has one flagellum surrounded by a collar

Archoecytes

Amoeboid cells that move about in the mesohyl with many functions

Sclerocytes

Specialized cell type that secrete spicules

Spongocytes

Specialized cell type that secrete sponging

Collencytes

Specialized cell type that secrete fibrillar collagen

Lophocytes

Specialized cell type that secrete large amount of collagen

Pinacocytes

Thin, flat, epithelial like cells that cover the exterior and interior surfaces of sponges almost like real tissue

Myocytes

Circular bands around oscula, help regulate flow of water, formed by pinacocytes

Fragmentation

Sponge breaks into parts that are capable of forming a completley new sponge

External buds

Small individuals that break off from parents that have reached a certain size

Internal buds or gemmules

Formed by archeocytes that collect in mesohyl and coated with tough sponging and spicules that can survive harsh environmental conditions

Micropyles

Line cells with gemmules, escape through special opening, and develop into new sponges, special opening is called

Gemmulation

A adaptation to changing seasons and for colonization of new habitats

Viviparous

Sponges that have choanocytes that phagocytize the sperm and transform into carrier cells that transport sperm through the mesohyl and to oocytes to form zygote

Oviparous

Sponges release both sperm and oocytes into water for external fertilization

Micromeres

Flagellated cells that are small and located at anterior end

Macromeres

Large nonflagellated cells located at posterior end

Cytoplasmic bridges

Connects choanoblasts and archeocytes with trabecular reticulum

Choanoblasts

Unusuall cells that make flagellated outgrowths called collar bodies whose flagella beats to move water like choanocytes