porifera - biol2200 - u of m

how do metazoans differ from other eukaryotes

• multicellular

• heterotrophic

• ingestive nutrition

• unique style of tissue formation through embryonic germ layering

what is the broadest clade of organisms that:

• is heterotrophic

• multicellular

• eukaryotic

• undergoes embryogenesis by way of tissue layering

metazoans

what feature of sponges allowed scientists to deduce that they are plants and not animals

their suspension feeding

what animal phyla were sponges originally classified under? why

cnidaria. believed to be radially symmetric

how many classes of sponges are there? what are they

4

1. demospongia

2. calcarea

3. hexactinellida

4. homoscleromorpha

what is the habitat of sponges

mostly marine, some freshwater, some can also live above the water column

sponges contain important compounds. what are the functional benefits of these compounds

• antibacterial

• antiviral

• antinflamatory compounds

which of the following is false about sponges (might be more than one)

a. sessile

b. it is debatable whether or not they lack tissues

c. they have organs

d. lack symmetry

e. lack true germ layers but have functional tissues

f. have choanocytes

g. have neurons

h. motile larval stages

c. they have no organs

g. they have no neurons

why is it debatable whether or not sponges have tissues

they lack true embryonic germ layers but contain different cell types specialized for distinct functions “functional tissues” (ie pinacoderm)

what are the unique flagellated cells of sponges called?

choanocytes

sponges have no neurons. but their _____ is sensory due to its _____ which detects ____

oscullum, cillia, water flow

are the larval stages in sponges sessile or motile

motile, as sponges are lecithotrophic

what does it mean that sponge larval stages are motile and lecithotrophic

the larval stages feed on maternal reserves (yolk sac) to fuel maternal development so they can move away

sponges have secondary metabolites mostly for ______

defense

the name porifera is derived from the ____ of sponges

pores

what is the main opening of sponges called

oscullum

____ sponge class is the largest sponge group while homoscleromorpha has lumpy surfaces

demospongia

what organisms give sponges their colour?

their symbiotic relationships with other animals like algae bacteria etc living in them

t/f, sponges have secondary metabolites mostly for defense

t

how do sponges move

• their larval stages which are motile

• some sponges “walk” over rocks, using lobelike extensions of their body which grow, elongate and disappear sometimes leaving progeny in their wake

what are the functions of the choanocyte

• generates current for:

  • feeding

  • gas exchange

  • removal of wastes

• captures food particles

• capture sperm

• gas exchange

• removal of waste

_____ drives water flow in sponges

choanocytes with beating flagella

the _____ is known as the mesoglea in sponges

mesohyl

how many cell layers do sponges have? what are they? what is between them?

2, pinacoderm and choanoderm, mesohyl

what is the mesohyl

the noncellular, nonliving gelatinous matrix with spicules and sometimes collagen fibers. it shapes plasticity and gives sponges their shaped

what is the difference between dermal pores and ostia

dermal pores

• not in asconoids

• opening surrounded by several cells

ostia

• opening surrounded by 1 cell

pinacocytes form the ____

while choanocytes form the ____

pinacoderm. choanoderm

what type of cells are in the mesohyl?

archeocytes, sclerocytes, spongocytes, collenocytes, lophocytes

how are archeocytes and sclerocytes, spongocytes, collenocytes, and lophocytes similar and diferent

similar

• all found in the mesohyl of sponges

different

• archeocytes

  • totipotent stem cells, can change from one type to another (differentiate reversibly )

  • important for digestion, food transport and development

• sclerocytes

  • irreversibly/specialized cells

  • produce spicules

• collenocytes

  • specialized cells

  • secrete skeleton (collagen)

• lophocytes

  • specialized cells

  • secrete skeleton (collagen)

• spongocytes

  • specialized cells

  • secrete skeleton (spongin which is a fibrous collagen)

what cells in the mesohyl are specialized to secrete the skeleton (collagen) how is the spongocyte a little bit different from these cells

lophocyte, collenocyte, and spongocyte

spongocyte secretes spongin which is a fibrous collagen

what are archeocytes?

• amoeboid cells

• totipotent (akin to stem cells in that they give rise to other cell types)

• important for:

  • digestion, food transport, and excretioon

  • development

which of the following are true about sponges

a. they can reaggregate after being mechanically dissociated

b. functional sponges can reform in 2-3 weeks

c. their cells display cellular self-recognition

d. all of the above

d

how many porifera body forms are there? how do they vary?

3

vary in

• size and shape of spongocoel

• number and arrangement of feeding chambers in body wall

how are the pores in sponges formed

the porocytes form the ostia

describe the path of water in an ascnoid sponge

1. ostia

2. atrium/spongocoel (over choanocytes)

3. out the oscullum

t/f

in an asconoid sponge, water comes in through the dermal pores, into the spongocoel (over the choanocytes) and out the oscullum

f. asconoid sponges dont have dermal pores, they have ostia

in ascnoid sponges, what layers do the porocytes go through

all of them

describe the path of water in a syconoid sponge

1. dermal pore

2. incurrent canal

3. prosopyle

4. choanocyte chamer

5. apopyle

6. atrium

7. osculum

the synconoid form is produced by the folding of 2 layers leading to thickening. what are these 2 layers?

choanoderm and pinacoderm

what structures important for water flow do syconoid sponges have that asconoids have / dont have

similar

• spongocoel

• oscullum

• choanocytes

different

• synconoids have: dermal pores, incurrent canals, prosopyle. apopyle,

• asconoids: have ostia

in some syconoid sponges, the mesohyl may also thicken and appear to have 2 layers. what is this thicker outer layer called

ectosome, remember it is the thickening of the mesohyl and the thicker layer

in a synconoid sponge, what is the opening to the incurrent canal called?

dermal pore

what is the incurrent canal of a synconoid sponge lined with?

pinacoderm.

the incurrent canal in a syconoid sponge is formed by the folding of _____ layer

pinacoderm

t/f

in a syconoid sponge, the dermal pore is formed from a single porocyte

false. not a single porocyte

the choanocyte chamber is formed from a folding of _____ layer

choanoderm

water passes through the apopyle into the ______, leaving the syconoid sponge through the _______

spongocoel, oscullum

____ is the wide opening from the choanocyte chamber to the atrium through which water flows out

apopyle

what are some differences between the syconoid and leuconoid sponge

leuconoid

• has excurrent canals

• subdivided choanocyte chamber

• increased choanocyte chambers

• smaller choanocyte chambers

describe the flow of water in leuconoid forms'

1. dermal pores

2. incurrent canals

3. prosopyle

4. choanocyte chamber

5. apopyle

6. external canal (atrium)

7. oscullum

what body form is found in all 4 sponge classes

leuconoid

how much water do sponges pump per day? larger sponges? why is pumping water so important for sponges

23litres/day. larger=23 litres per 10-20 secs. it is how they feed. need it to go to choanocyte

what is suspension feeding

removal of suspended food particles from the surrounding medium

how do sponges feed

1. some sort of filtration system, ie suspension feeding

2. can capture/trap their food

what is the feeding process for suspension feeders like

1. transport water past their feeding structure

2. remove the particles

3. transport captured particles

t/f

many suspension feeders have optimal particle size but some can preferentially select “enrinched” particles/food over non-food particles using specialized feeding structure (cillia, flagella, setae etc)

t

the generation of current is energetically expensive for suspension feeders. what is the cost of pumping in sponges, what % of their total metabolism

1-26%

what do suspension feeders feed on?

• bacteria

• zooplankton (animals)

• phytoplankton(plants)

• picoplankton

• detritus

what type of environments might you find a suspension feeder

bodies of water w tons of h2o flow

what are the diff types of suspension feeders?

1. passive: go with flow but require good retaining structures, dont make own flow (cnidarian)

2. active: alter the flow to create feeding currents (bivalves)

3. facultative: use both passive and active, switching back and forth when flow changes (sponges)

4. combined: do both passive and active at once(sponges)

what type(s) of suspension feeding do sponges utilize

1. combined (use both active and passive suspension feeding, alternating between the two depending on how high the velocity of flow is) or

2. facultative (use both active and passive simultaneously)

describe passive suspension feeding. give an eg of a phylum that utilizes this method

go with the flow but require good retaining structures

eg cnidarians

describe active suspension feeding. give an eg of a phylum that utilizes this method

alter the flow to create feeding currents

eg bivalves

describe facultative suspension feeding. give an eg of a phylum that utilizes this method

use both active and passive suspension feeding, switching back and forth when the flow changes (if high or low velocity)

eg sponges

during high velocity flow, facultative suspension feeders use _____ suspension feeding and ______ when low velocity

passive, active

describe combined suspension feeding. give an eg of a phylum that utilizes this method

do both active and passive suspension feeding at once

what does this tell us about suspension feeding through a leuconoid sponge

water comes into the leuconoid sponge through the dermal pores relatively slowly, passes through the flagellated chambers extremely slowly as the choanocytes capture food particles, and exits through the osculum very quickly

what is digestion and hydrolysis

Digestion is the process of breaking down food into smaller components suitable to the nutrition of cells, digestion is done through hydrolysis.

hydrolysis is the chemical breakdown of food components through the addition of water.

compare and contrast extra and intracellular digestion

similar

• both digestive processes

different

• extracellular: digestion occurs outside cells, often in a digestive cavity (gut chamber) or system;

• intracellular: digestion takes place within cells, through phagocytosis or pinocytosis.

what are the two processes of intracellular digestion

phagocytosis and pinocytosis

define phagocytosis

phagocytosis is a type of intracellular digestion process during which extensions of the cell membrane encircle a food particle (or foreign microbe etc), forming an intracellular food vacuole which pinches off and into the cell

why is phagocytosis considered an intracellular process?

intercellular because the cell membrane of the food vacuole pinches into the cell. the membrane and the contents of the food vacuole are no longer part of the cell’s outer membrane, and are considered intercellular and the resulting digestive process takes place within the cell

what is a food vacuole

a food vacuole is intracellular, membrane bound structure formed during phagocytosis; after the cell membrane surrounds the particle and pinches into the cell

during phagocytosis, ______ carries wastes to the cell surface

digestive vacuole

describe the role of pseudopodia during phagocytosis

they are fake arms that come out of the cytoplasm to engulf the molecule

what is the reverse of phagocytosis

exocytosis

the lysosome is involved in phagocytosis. what does the lysosome contain? where does it come from? what is it fused with?

lysosome contains digestive enzymes

comes from golgi body

fuses with food vacuole

what is pinocytosis? describe the process.

• drinking by cells

• a specialized form of phagocytosis during which molecule sized particles (dissolved in body fluid) are taken up by the cell

• during this process,

  1. minute invagnations (pinocytotic channels) containing are formed on the surface of the cell,

  2. fill with liquid from the surrounding medium (which includes dissolved organic material)

  3. pinch off to enter the cytoplasm as pinocytotic vessels

during pinocytosis,

_______ attach to binding sites on the ______ of the cell, which then form ______ channels which pinch off into the cytoplasm as ______ vessels

nutritive solute molecules

plasma membrane

pinocytotic

pinocytotic

where does pinocytosis usually occur

in cells lining a body cavity/ gut, where extracellular digestion has alr taken place or in seawater, directly up taking dissolved organic matter (DOM)

what are some similarities between phagocytosis and pinocytosis

similar

• both processes of intracellular digestion

• both involve the engulfment of “food” particles at the cell surface

what are some differences between phagocytosis and pinocytosis

phagocytosis

• eating of the cell

• bigger invaginations

• sponges mostly use phagocytosis

pinocytosis

• drinking of the cell

• more specialized form of phagocytosis

• minute invaginations

• occurs where extracellular digestion has already taken place and cells lining body cavities or guts

describe pinocytosis? where does it take place

pinocytosis occurs in cells lining body cavities/gut where extra cellular digestion has already occurred as well as uptake of dissolved organic matter (DOM), or in bodies of seawater (sponges, placozoans)

digestion of solute molecules dissolved in a solvent. the solute binds to the cell membrane and it pinches inward forming a pinocytotic channel which pinch off as pinocytotic vessels

what are the 6 processes involved in feeding and digestion? how are they constrained from organism to organism

1. locate

2. select

3. capture

4. invest

5. digest

6. use it

constrained by organisms body plan

what is suspension feeding

removal of suspended food particles from surrounding medium

describe the feeding of sponges (what type of feeders are they, how is the size of particles determined)

• sponges are suspension feeders, filtering water and selecting particles based on size

• intraceullar digestion largely by phagocytosis using motile archaeocytes or choanocytes

• the size of the particles is determined by the size of the the openings of dermal pores, ostia, prosopyles, apostles etc

sponges use intracellular digestion by phagocytosis, what structures conduct this

motile archeocytes and choanocytes

describe archeocyte phagocytosis

digestion in food vacuole formed during capture of food by acheocyte

t/f sponges have no true digestive tract

t

the size of particles that are involved in suspension feeding in sponges is determined by

the size of the openings of dermal pores prosopyles ostia etc

____ conduct phagocytosis in sponges

motile archaeocytes and choanocyte

compare and contrast archeocyte vs choanocyte phagocytosis

archeaocyte

• particles are trapped by food vacuoles in archaeocytes and digested there

choanocyte phagocytosis

• food particles are trapped by choanocytes where some digestion occurs and passed unto the choanocyte (or other wandering amoebocyte) where final digestion occurs

what are the three cells (notice cells) where trapping by phagocytosis occurs

• pinacoyte (sponges outer surface and lining of cells)

• choanocytes

• amoebocytes

t/f, trapping by phagocytosis doesn't occur on sponges outer surface and the lining of canals by pinacocyte

f. it does

in what kind of sponges would we see choanocyte phagocytosis more than archaeocyte phagocytosis. why?

asconoid or very simple syconoid sponges because they have reduced mesohyl layers, so, less archaeocytes, therefore choanocytes would be doing most of the work

how are sponges important sources of food in oligotrophic (low food) environments

their choanocytes don’t last very long and are expelled through the osculum before new choanocytes are generated (sponge loop). therefore, expelled choanocytes act as sources of food for other organisms

t/f feeding by pinocytosis (DOM) is aided by microbial symbionts

t

in sponges, simple diffusion occurs across the ____ tissue layer and wastes are continuously removed through the ______

choanoderm, oscullum

what are the functional benefits of sponges sneezing

sponges contract to remove unwanted/clogged particles out of their incurrent canals or to blow water out their osculum

what are the two types of skeletal elements? give examples of each

1. inorganic minerals like calcium carbonate, silica

2. organic structural protein like collagen