Lab #2: Microscope and Sponges

compound light microscope

higher total magnification
able to see more detail
able to see very small objects

dissecting microscope

able to see objects in 3D
larger view (larger field of vision)
able to look at live specimens (that are not microscopic)
able to place light anywhere to view specimen

Phylum Porifera (sponges)

most primitive animal phylum
no true tissues, no organization
aquatic, mostly marine, some freshwater
no mouth nor anus
asymmetrical

Three classes under Phylum Porifera

Class Calcarea
Class Hexactinellida
Class Demonspongia

classes of sponges are based on ____________

characteristic structures and body organization

mesohyl

gelatinous matrix with scattered cells

pinacocytes

flattened epithelial (outer) cells

choanocytes

collar cells
create water currents in canals and chambers

spicules

made of calcium carbonate, silica, or fibers of spongin
provide structural support

gemmules

internal asexual buds in freshwater
produced during period of cold or drought and can survive to produce a new sponge body when conditions improve

syncytial

having many nuclei contained within a single plasma membrane
can be the outer tissue layer in some sponges

amoebocyte

within the body wall of a sponge, a specialized cell that crawls about and delivers nutrients from the choanocytes to the rest of the body cells

ostium/ostia

small incurrent pores where water enters the body of the sponge

oscula

one or more large excurrent pores where water leaves the body of a sponge

spongocoel

large central cavity of the sponge

the three type of sponge canal systems

asconoid
syconoid
leuconoid

asconoid sponge

incurrent pores
spongocoel lined with choanocytes
osculum
one large flagellated chamber

syconoid sponge

ostium
incurrent canals
radial canals lined with choanocytes
spongocoel
osculum

leuconoid sponge

pores
incurrent canals
radial cannals
flagellated chambers with choanocytes
osculum
much thicker body wall
is found in all of the larger sponges

class Calcarea

calcareous sponges
spicules make of calcium carbonate (CacCO3)
all marine
all canal systems are found in this class

class Hexactinellida

glass sponges
spicules are siliceous (SiO2) and are 6-rayed
all marine
syconoid and leuconoid canal system
unique trabecular (porous material of hard and soft tissue) network

class Demospongiae

commercial sponges

siliceous spicules, but not 6-rayed

AND/OR

fibers of spongin

all leuconoid

most marine; some freshwater

the importance of sponges

- break down material into food for other animals in coral reef systems
- food for hawksbill sea turtles (and other turtles)
- filters bacteria and contaminants in water
shelter for other animals