Zoology Chapter 12 Sponges

Phylum Porifera and Placozoa

What are the advantages of multicellularity?

Increased surface area for metabolic activities; highly adaptive path towards larger body sizes; leads to division of function & greater complexity

Choanoflagellates

aquatic unicellular eukaryotes; each cell has a flagellum surrounded by a collar of microvilli; sponges have something similar called- choanocytes; closest relative to multicellular animals

Phylum Porifera

Sponges; simplest multicellular animals; asymmetry or radial symmetry; no mouth, digestive tract, or tissues; has mesophyll, spicules, and spongin; about 8600 species today; few mm to over 2 m in diameter

mesophyl

Gelatinous matrix of protiens where all other cells reside; contains skeletal elements

spicules and spongin

tiny silica or calcium carbonate(spicules) and collagen proteins(spongin) skeletons that supports the matrix of a sponge

Sponge Ecology

Free-swimming embryos & sessile adults; can attach to anything submerged; shape & size dependent on environment & space

What biochemicals do sponges & microorganisms that live on crabs, fish, etc produce?

Antimicrobial, antiviral, antiparasitic activity

How do sponges Filter feed?

Suspension feeding; collecting suspended particles from the water

Dermalostia

pores used to draw water into an asconoid sponge

What is A

Osculum

What is B

Pinacocyte

What is C

Chanocyte

What is D

Ostium

What is E

Spicule

What is F

Porocyte

What is G

Spongocoel

Pinacoderm

the outermost layer of cells in sponges

Chanocytes

Ovoid cells tat line canals & chambers; one end is embedded in the mesophyl; Flagellum & surrounding collar extend from exposed side

Flagellum of Choanocyte structure

collar consists of microvilli connected to each other by fine microfibrils = fine filtering device; the beating flagellum moves water through the collar sieve; large particles are trapped in the collar mucus & are phagocytized

Microvilli

;used to trap food in Sponges

Phagocytosis

a process in which specialized cells called phagocytes engulf and destroy foreign particles, such as bacteria, viruses, and dead cells

Describe a Asconoid Sponge’s form and function

Simplest body organization; water is drawn through dermal ostia(porocytes), is drawn into the spongocel(central cavity) by beating flagella of choanocytes(also traps & phagocytizes food particles), the is expelled from top through osculum

Describe a Syconoid Sponge’s form and function

Tubular body with single osculum; thicker and more complex spongocoel with outward folding for more surface area; water enters through dermal ostia, travels into radial canal through prosopyles, choanocyte cells trap food and move water that exits radial canal into spongocoel through apopyles, before being expelled at top through osculum

Describe a Leuconoid Sponge’s form and function

Most common and complex organization with greatest surface area for food gathering; Choanocytes line the walls of small chambers; permits an increase in size= can filter all water; water is drawn into chambers through incurrent canal then exits chambers through excurrent canals, the expelled at the top through osculum(oscula)

What is A

Spongocel

What is B

Osculum

What is C

Apopyle

What is D

prosopyle

What is E

Spicule

What is F

Incurrent canal

What is G

Dermal Ostium

What is H

Radial canal

What is A

Osculum

What is B

Excurrent canal

What is C

flagellated chamber

What is D

Incurrent Canal

What is E

ostium

What is A

Archaeocyte

What is B

Pinacocyte

What is C

Collencyte

What is D

Mesohyl

What is E

Choanocyte

What is F

Spicules

Pinacocytes

thin flat, epithelial-like cells that make up the pinacoderm; closest thing to a tissue; some are modified into mycocytes, located around oculsa or pores to contract to regulate water flowa

Choanocytes

ovoid cells that line canals & chambers; one is embedded in the mesophyll

Choanocyte Flagellum

extend from exposed side; collar consists of microvilli connected to each other be fine microfibrils = fine filtering device; beating flagellum moves water through collar sieve; large particles are trapped in collar mucus &are phagocytized

Archaeocytes

ameboid cells that move about the mesohyl and receive particles form choanocytes for intracellular digestion; can also phagocytize particles at the pinacoderm

Archaeocytes specialized cells

Sclerocytes, spongocytes, collencytes

Sclerocytes

specialized cells that create spicules

Spongocytes

specialized cells that produce spongin, secrete spongin fibers

Collencytes

secrete collagen

Asexual reproduction for sponges

budding

Sexual reproduction for sponges

Monoecious; both female and male sex cells in one individual; sperm and oocytes are usually produced by modified choanocytes; most are viviparous, some are oviparous

Oviparous

Releases sperm and eggs into water; offspring develops outside of mother

Viviparous

Live birth; offspring develops outside

Development of sponges

Free swimming larva(parenchymula) settles, flagellated cells migrate to the interior & become choanocytes

External buds

Fragments or buds break off

Gemmules

Internal buds; collected in Mesohyl; are covered with a tough spongin and spicule coat; can survive harsh, environmental conditions

Four sponge classes

Calcispongiae, Hexactinellida, Demospongiae,
Homoscleromorpha

What is A

Homoscieromorpha

What is B

Calcispongiae

What is C

Deospongiae

What is D

Hexactinellida

Class Calcispongiae

Calcium carbonate, Monaxon(straight) spicules or with 3-4 rays; <10cm in length; tubular or vase shaped; asconoid, synconoid, leuconoid

Class Hexactinellida

Glass Sponges; deep sea, radial symmetry, tube or vase shaped with spicule roots; siliceous 6-rated spicules(commonly bound together in a network); length 7.5 cm to 1.3 m: synconoid and leuconoid

Choanoblasts

2 collar bodies; responsible for the formation of cartilage by actively producing the extracellular matrix components that give cartilage its structure and strength

Class Demospongiae

95% of sponges; May have silious spicules(not 6 rayed) or just spongin; length and shape are highly variable; leuconoid structure; most our marine, one freshwater family

Class Homoscleromorpha

Two clades:one with spicules and one without; length and shape highly variable; Leuconoid; occur in cryptic marine habitats

Pinacoderm layer is an incipient tissue(early stage; has a true basement layer; cells connected via one type of cell junction(two tissues in one

Silicous Demospongiae

Predatory sponges that live in deep nutrient poor water. They’re coated with tiny hook-like spicules that ensnare tiny crustaceans that grow over prey and digest them. Have no choanocytes and internal canals

Phylum Placozoa

Tiny marine animals 2 to 3 mm in length; plate like body with no symmetry organs, muscular system or nervous system; no ECM but gene suggest otherwise, have four cell types, external digestion(secretes digestive enzymes)

What is A

Contractile fiber cell

What is B

Dorsal epithelium

What is C

Ventral epithelium