Sponges
Kingdom Animalia
Phylum Porifera
Vase sponge
Porifera
 Porifera means “pore-bearing” and refers to the numerous pores and
channels that permeate a sponge’s body.
 Phylum Porifera includes about 8000 species almost all of which are
marine and come in many colors
 About 150 freshwater species, color green, members of the family
Spongillidae.
 Sponges occur worldwide at all latitudes from the intertidal zone to the
deep sea.
 Range in size from a few millimeters to 2 meters across
 Some tropical sponges can live 200 years, the largest are thought to be
thousands of years old
 Temperate sponges species live only a few years
Sponges are plastic
 Sponges may be bulky, spherical or




tree-like, or appear as incrustations
vary in thickness and are found in all
colours
a single species can vary in shape and
colour depending on its habitat.
appearance due to environment
(light levels, hydrodynamics, etc.)
Have few predators: sea slugs graze on
them
Porifera: Simplest of all animals
 Sponges have no tissue or organs,
o Contain specialized cells but no other
organization level
 filtration of water is carried out by their aquifer
system: channels and small chambers lined with
specialized cells (choanocytes) that create currents of
water and retain nutritive particles
 gain their nourishment from microscopic
detritus, bacteria, and micro-algae suspended in
the water.
 Sponges are therefore suspensivores
WATER OUT
Water Flow
Through the
Sponge
WATER IN
Osculum
Porifera feeding
 Sponges are sessile (they don’t move)
 depend on water movement to bring
in food and oxygen and remove wastes.
 Sponges generate their own flow of
water having a unique water current
system.
Porifera feeding
Water enters
Through many small pores called ostia
and exits through fewer, larger oscula.
Openings are connected by a series of canals,
which are lined by choanocytes
(the flagellated collar cells) that
maintain the current and filter out food particles.
Choanocytes
Porifera feeding
 The choanocyte’s collar consists of microvilli
joined together by delicate microfibrils,which filter
out tiny food particles.
 The beating of the flagellum draws water through
the collar and out the top.
 Particles too big to pass through the collar get
trapped in mucus and slide down the collar to the
base where they are phagocytized.
Porifera feeding
 Sponges can filter enormous volumes of water as much
as 20,000 times the volume of the sponge in 24 hours.
 Sea water contains about 65 milligrammes of silicon
per litre. Demosponges and hexactinallida Sponges are
able to extract the silicate from the water and
precipitate it as the silica.
 Sponges mostly consume bacteria and may filter as
much as 90% of those passing through.
Amoebocytes
Skeletal Structure of the Sponge
 Sponges are divided into three main classes based
on the structure of their endoskeletons: Calcarea,
Demosponges, and Glass Sponges.
 Skeleton made of network of protein fibers called
Spongin, silk-like scleroprotein
 Spicules are hard spear or star-shaped structures
 Spicules made of CaCO3 (limestone) or silica
(glass)
Spongin
Venus
flower basket
Spicules: silica or
calcium carbonate
sponge_spicules_06_300x310_rathl
in_sponges_divernet.com
sponge_spicules_09_600x400
Venus'%20Flower%20Basket%20(Euplectella%20aspergillum)%20%7C%20Flickr%20-%20Photo%20Sharing!.webarchive
Reproduction
o Sponges reproduce asexually
by budding
o Also reproduce by
fragmentation (pieces break
off & form a new sponge)
o Sponges can regenerate
(regrow) lost body parts
through mitotic cell division
(asexual)
o This property makes
spongiculture possible
Survival Pods
o Gemmules are specialized buds made to survive
harsh weather (hot or cold)
o Contain food, amebocytes, and a protective
covering of spicules
o Released when a sponge dies
o Resist dessication (drying out)
o Become adult sponge conditions become
favorable
Reproduction
o Sponges are hermaphrodites
(produce both eggs & sperm)
o Sponges reproduce Sexually by
releasing eggs & sperm into the
water from the Osculum
o Cross-fertilize each other’s eggs
o Free-swimming larval stage
called Dipleurula
Sponge
releasing eggs
and sperm
Azure Vase Sponge
Barrel sponges
Rope sponges
Sponge skeleton
 consists of fibres of spongine, a sort of collagen, which
gives these sponges "suppleness, elasticity, and
softness".
 Hippospongia communis (Lamarck, 1814), the common
or "honey comb" sponge, is the species most often
caught in the Mediterranean.
 It may grow very large (several dozen centimetres or
about a foot in diameter). Its network of channels is the
most "cavernous", giving it a remarkable power of
absorption
Carnivorous / Symbiotic
 A few sponges capture small prey, such as crustaceans.
 Members of the family Cladorhizidae capture their
prey using spicules that act like velcro to hold the prey.
Cells then surround and digest prey extracellularly.
 Some sponges supplement their filter feeding by
hosting symbionts such as green algae, dinoflagellates
or cyanobacteria.
Types of cells in Porifera
 Sponge cells occur scattered through a gelatinous
matrix called mesohyl.
 Spicules are distributed through the mesohyl as are
several different specialized cells types.
Sponge cell types
 Archaeocytes: move around within the mesohyl.
They are ameboid in appearance and carry out
several tasks.
 Phagocytize particles and receive particles for digestion
from choanocytes.
 Can differentiate into other specialized cell types.
 Secrete structural components. Specialized
archaeocytes called sclerocytes, spongocytes and
collenocytes secrete respectively spicules, spongin and
collagen.
Sponge cell types
 Choanocytes: (collar cells) engage in filter feeding.
One end is imbedded in mesohyl and the other end
protrudes.
 The protruding end of the choanocyte has a flagellum
that moves water through a mesh-like collar where
small particles are trapped.
 Porocytes: These are tubular cells that in the simplest
type of sponge (asconoid sponges) form tubes through
the wall of the sponge and allow water to flow into the
central chamber
Sponge cell types
 Pinacocytes: Layers of pinacocytes form a flat, thin
epithelium-like layer
 Pinacocytes cover exterior and some interior surfaces.
 have some ability to contract
 arranged in bands around pores and use to regulate the
flow of water in and out of the sponge.
Canal systems
 Most sponges have one of three types of canal system:
 Asconoid
 Syconoid
 Leuconoid
 These systems differ from in each other in the
increasing complexity.
Sponge reproduction
 Sponges reproduce both sexually and asexually.
 Most sexually reproducing species are
hermaphrodites (individuals produce both male
and female gametes at different times).
 Sperm are shed into the water and taken up by
other sponges. Individuals with eggs use special
cells called archaeocytes to transport sperm to the
eggs.
Sponge reproduction
 Zygotes develop into ciliated larvae that are released
into the water and eventually settle and develop into a
sponge.
 Asexual reproduction is either by budding or more
commonly the production of gemmules which are
clusters of cells surrounded by a protective coat.
Totipotency
 Sponges possess several different types of cells.
 All sponge cells are totipotent and can give rise to
any of the other types of cell.
 A single cell can give rise to a new sponge
 Can self-assemble with other cells into a sponge
a sponge separated into its
constituent cells will
spontaneously reassemble
Groups of sponges
 There are three classes of sponges:
 Class Calcarea - spicules are made of calcium
carbonate
 Tend to be small (<10cm) and tubular or vase shaped
 Class Hexactinellida –six-rayed siliceous spicules
bound in a glasslike lattice
 Nearly all are deep sea forms
 Body of hexactinellids consists of a single, syncytial
tissue (mass of protoplasm containing many nuclei, but
not divided into cells)
 Class Demospongiae
Demospongiae
 Includes about 80% of all species
 Includes the freshwater Spongillidae
 Spicules siliceous, spongin or both.
 All members are leuconoid (more complex canals)
 Comprise most of the large sponges
 Loggerhead sponges may be 5 ft in diameter and
weigh 700 lbs
 Includes the bath sponges, which have only
spongin skeletons.
Origins of multicellularity
 Choanocytes the collar cells of sponges bear a striking
resemblance to free-living unicellular choanoflagellates.
Choanoflagellate
Choanocytes
1424u giant sponge
1455u purple sponge