Chapter 12: Sponges and Placozoans Flashcards Preview

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Flashcards in Chapter 12: Sponges and Placozoans Deck (56):

Multicellularity avoids what issue?

surface-mass problems


Metazoans are?

multicellular animals


Choanflagellates? Characteristics?
-flagellum does?
-microvilli collect?
-sessile or free moving?
-they resemble ?
-ancestral to ?

-solitary or colonial aquatic
- cell type, which has a flagellum surrounded by collar of microvilli
I> beating of flagellum draws water into collar ...collects mostly bacteria
-sessile mostly
I> one species attaches to floating diatom colonies
-resemble sponge feeding cells
-are sponge choancytes ancestral to choanoflagellates


Phylum Porifera? Features?
-describe body?
-choanocytes funct?
-body is a ?
-how many species ?
-habitat ?
-Sessile sponges food?

- sac like bodies perforated by many pores
-use choanocytes to move water
-aquatic filter = body
-~15,000 species
- most are marine...some live in brackish water
- sessile sponges are filter feeders


Embryos in Phylum Porifera are??

free swimming but adults are always attached.


Phylum porifera symmetry ?

some appear radially sym but most are just irregular


Forms of Porifera? (4)

Encrusting, finger, variable and tube sponges.


Growth and the environment with Phylum Porifera?

-Growth depends on characteristics of the environment
- many animals live as commensals or parasites in or on sponges.


Predators of Porifera?

very few.
they have an elaborate skeletal structure and often have a noxious odour.


Skeletal of Phylum Porifera??

can be fibrous or rigid...


Rigid skeleton consists of ?

calcareous or siliceous spicules!


Fibrous portion of skeletal structure in Porifera?
- found where?
-micro-algae significance ..spicules?

- collagen protein fibrils in intercellular matrix....several types of one form of collage, spongin exists.
-harbour micro-algae and cyanobacteria on the body surface and deep inside the body......this presence of photosynthetic organisms means spicules can transmit light into the body.


What are the three classes of Porifera ?

-Calcarea, Hexactinellida and Demospongiae.


Spicules common to the three classes? Calcarea, Hexactinellida, and Demospogiae !

- calcium carbonate spicules with one, three or four rays.
-glass sponges with six rayed siliceous spicules
-siliceous spicules around an axial filament, spongin fibres or both.



outer layer of cells


Dermal Ostia?

small incurrent pores on the outer layer of cells which water enters canals through.


Once water enters via the dermal ostia it goes by __________ which trap and _________ food.

choanocytes, phagocytize


Choanocytes line some canals doing what:?(2)

keeping the current flowing via flagella
trap and phagocytize food passing by.


When it comes to food sponges _____________ consume food particles.



The smallest food particles are taken into the ________ by _______.

choanocytes, phagocytosis


Protein molecules are taken in by?

Pinocytosis ......via fluid acquisition by a cell in a which specific receptors bind ions/molecules present on plasma membranes which are invaginated and pinch off to form small vasicles.



...closest to true tissue...
epithelial like cells making up the pinacoderm...ingest food via phagocytosis at the sponge surface....can become specialized for contractile purposes to help regulate surface area...(myocytes) circular bands around pores or oscula....



ameboid cells that move in the mesohyl ...can ingest food at pinacoderm by phagocytosis or takes in particles from the choanocytes for digestion.....


Archaeocytes give rise to? (4) define each.

Sclerocytes- secrete spicules
Spongocytes- secrete spongin fibres
collencytes- secrete fibrillar collagen
Lophocytes- secrete larger quantities of collagen..morphologically different than collencytes.


What are the three types of canal systems in sponges?

Asconoid, Syconoid, and Leuconoid.


-water enters?
-canal is lined with? that?
- what class only has asconoids

-simplest system
-small and tube shaped
-wanter enters the large cavity known as the spongocoel which is lined with choanocytes....the flagella pull water through....all Calcarea is the only class that this type occurs in
ex: Leucosolenia and Clathrina..


-body type
-radial canals? lined with?
-enters radial canals via?
- spongocoel is lined by?
-digestion occurs via?
classes involved?
water enters the spongocoel via? by?

-similar to asconoids but larger and has a thicker body wall.
-wall contains choanocyte lined radial canals that empty into spongocoel.
-water enters radial canals via prospyles.
-spongocoel is lined with epithelial cells not choanocytes..
-food is digested by choanocytes..
-water enters the spongocoel via internal pores known as apopyles via flagella drawing water to it.
-calcarea nd hexactinellida


Syconoids pass through a ________ stage in development but do not form highly _____________ colonies. The flagellated canals form by ____________ of the body wall.

asconoid stage, branched, evagination


Most complex and are ______ with many _______
Clusters of ____________ chambers are filled from incurrent canals and discharged to _______excurrent canals.
Most sponges are _______.
This system _______ flagellated surfaces compared to ______.
Meaning more collar cells can meet ________ demands.
Large sponges filter ________ litres of water a day.
Point form description of water flow....GO

larger, oscula, flagellated, leuconoid, increases, volume, food, 1500..
basically water flow goes ..... water->dermal ostium--> incurrent canal lined with pinacocytes--->enters via Prosopyles--> radial canal lined with choanocytes---> apopyle--> spongocoel--->osteum--> water environment..


Mesohyl whats up with that?
absence of organs wtf?

gelatinous extracellular matrix...connective tissue or sponges....absence of organs means all fundamental processes are at individual cellular levels.


What are the visible activities of sponges yo?
shape? pores? movements?

-alterations in shape via local contractions, propagating contractions and closing and opening of incurrent and excurrent pores.
-movements occur slowly



-oval shaped cells with one end embedded in the mesohyl
-exposed end has one flagellum surrounded by a collar consisting of adjacent microvilli.
-forms a fine filtering device to strain food.
-particles too large to enter collar are trapped in mucous
-moved to choanocyte and phagocytized
-food engulfed via choanocyte is passed to archeaocytes for digestion.



when a sponge is wounded it can reorganize the part that is wounded or missing repairing it..


Somatic Embryogenesis ?
asexual reproduction yo?

complete reorganization/regeneration of an entire structure and function.
ex: cut a sponge into small bits and or dissociative cells aggregating can become entirely new sponges and develop from these...Regeneration by fragmentation is a form of asexual reproduction!


External buds?

small individuals that break off after reaching a certain size they detach from the parent float away to form new sponges or form colonies.


Internal buds (gemmules) ?

formed by archaeocytes that collect in mesohyl
coated with tough spongin spicules
survive harsh environmental changes
**fresh water sponges.
when the parent dies they lie dormant inside until the season/environmental conditions is habitable and escape via special openings called micropyles.


What stops internal buds from hatching?

- some species secrete a substance that inhibits germination as long as they are inside the parents body.
-others are inhibited by temperature cues..undergoing development at low temps


Most sponges are _________ in terms of reproduction.
sperm sometimes arises from?
In some Demospongiae and Calcarea...gametes develop from_____ and some derive gametes from_____...

monoecious.....containing cells that produce both sperm and eggs.
transformed choanocytes
choanocytes, archaeocytes...


-after fert??
-sperm comes from? goes to? carried by? goes to?

after fertilization the zygote remains in the parent deriving nutrition from it and a ciliated larva is released.
sperm is released into water by one individual and taken into the canal system of another.
choanocytes phagocytize the sperm carrying it to oocytes in the mesohyl.



both sperm and eggs are released into the water


after settling down?

free-swimming larva of most sponges which is solid bodied...once settled down the outwardly directed flagellated cells migrate to the interior becoming choanocytes in flagellated chambers.


Odd developmental patterns in some Calcarea and Demospongiae?
-Hollow ______ developes with ________ cells oriented toward the ____.
- The blastula then turns _____ aka ______.
-Flagellated cells or ________ of larva are located on the _____ end.
-Larger non-flagellated _______ located at the ______ end.
-Macromeres overgrow the micromeres during metamorphosis during _______.
-Flagellated micromeres become ______, ________ and _________.
-Non-flagellated cells give rise to __________ and _________.

- stomoblastula, flagellated, interior
-inside out, inversion
-micromeres, anterior
-macromeres, posterior
-choanocytes, archaeocytes and collencytes
- pinacoderm and sclerocytes.


Class Calcarea?
ex: Leucosolenia
ex: Sycon
-spicule type
- canal type

- spicules of calcium carbonate
-spicules are strate or have three, or four rays
-small with tubular or vase shapes
-drab in colour but some are bright yellow, green, red or lavender
ex1: small asconoid, stolonlike tubes, branching colonies.
ex2: solitary sponge, forms clusters via budding, syconoid, straight spicules around osculum..
-can be any of the three canal types.


Class Hexactinellida
made of? spicules?
connection to subsrate?
Trabecular reticulum?
canal type?

- glass sponges with six rayed spicules of silica(glass)
-all are deep sea forms mostly
-radial symmetrical
-stalks of root spicules attach them to substrate
-Spicular system forms network
-trabecular reticulum: made of a fusion of archaeocyte pseudopodia forms the chambers opening to spongocoel...largest continuous syncytial tissue in Metazoa.
-syconoid or leuconoid canal type


Between the bilayer of the trabecular reticulum in the collagenous mesohyl (note not gelatinous) are what two things?

archaeocyts and choanoblasts...


Choanoblasts ? (hexactinellida)

unusual cells that make flagellated outgrowths called collar bodies....layers of trabecular reticulum can be sheet like or tubular.


Hexactinellids lack?

pinacorderm or gelatinous mesohyll ..myocytes are absent.


Class Demospongiae
-percent of living sponge species here
-canal type
-marine/freshwater ? both ? one?
-expectancy of life cycle for fresh?

-95% of living sponge species
- spicules are siliceous but not six rayed...absent or bound by spongin.
-Leuconoid body form
-all marine except spongillidae (fresh water)
>fresh water ones die in autumn and flourish in summer


Marine Demosponges
ex: bath sponges

lack siliceous spicules
have spongin skeletons
most common sponge


Sponges appeared before the ?



Glass sponges expanded in the ?



Theory about sponges? They arose from???

Choanoflagellates ...but some corals and echinoderms have collar cells as well.....sponges acquire them late in dev


rRNA evidence suggests that Porifera??common ancestor?

-choanoflagellates and metazoans
-sponges and eumetazoa are sister groups with porifera splitting off before radiates and placozoans.


Medical use of sponges?????

presence in sponges themselves or their microbial symbionts of chemicals that may be used to control viruses, bacteria, tumours and fungi.....


Carnivorous Sponges?

feed on crustaceans
use sticky threads to capture
deep water habitat
cave dwelling sometimes...


Phylum Placozoa?
-sole species
-systems it does not have?
-cell layers?
-how it gets food!

-Trichoplax adhaerens
-no symmetry
-no muscular or nervous organs
-cell layers?
-dorsal epithelium
-thick ventral epithelium of monociliated cells and nonciliated gland cells...
-space between the epithelia contain fibrous cells within a contractile sycnytium...
-simplest known animal
-glides over food , secretes digestive enzymes and absorbs nutrients
-diploblastic .....epithelium rep ectoderm, ventral epithelium rep endoderm.

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