Phylum Porifera
Sponges
Porifera
• Sponges
– Living on Earth for at least
540 million years
– Most sponges live in the
ocean
• Arctic to the tropics
• shallow water to depths of
several hundred meters
– They are dry sponges were
use for
• Bathing
• Cleaning
Porifera
• What is a Sponge?
1. Sponges are placed in the phylum Porifera (poh-RIFur-uh) which means “pore-bearers.”
• Sponges have tiny openings, or pores, all over their bodies
2. Sponges are sessile, meaning that they live their
entire adult life
3. They have irregular symmetry
Porifera
• Why are sponges considered animals?
– Sponges are multicellular, heterotrophic, have no
cell walls and contain only a few specialized cells.
Water
flow
Porifera: Structure
• Specialized cells of sponges:
1. Collar cells or choanocytes – Use flagella to
move a study current of water through the
sponge.
2. Osculum – A large hole at the top of the sponge
3. Spicule – spike-shaped structure made of
chalklike calcium carbonate or glasslike silica
4. Amoebocyte – move around within the walls of
the sponge and carry food to other cells
Porifera: Digestion
• Sponges are filter feeders – take
microscopic food particles from
the water.
– As water moves through the
sponge, food is trapped and
engulfed by collar cells
(choanocytes) that line the body
cavity
– Then, food gets passed to
amebocytes who take the food to
the rest of the cells in the body
Porifera
• How do they breathe?
– Sponges rely on the movement of water through
their bodies to carry out body functions:
• Respiration – oxygen obtained from the water
• Excretion – removal of wastes into the water
Porifera
• How do they reproduce?
– Reproduction can be sexually or asexually.
– Adults produce gemmules which can withstand
harsh conditions and grow into an adult sponge
– Reproduce asexually by regeneration – tear of a
piece of sponge and a complete new sponge will
appear.
Porifera
• How important are sponges to the environment?
– Many sponges are large and have irregular shapes and
provide habitats
– Commensalism and partnerships
• EX: bacteria provide food and oxygen to the sponge while
the sponge provides protected area.
Porifera
• Types of Sponges
1. Calcareous sponges
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Found in shallow waters around the world
Spikes made of calcium carbonate (lime)
Porifera
• Types of Sponges
2. Glass sponges
•
•
Skeleton consists of crystalline silicon dioxide
Generally found in deep, tropical waters
Porifera
• Types of Sponges
3. Demospongiae (Bath sponges)
•
•
Skeleton is elastic (spongin) fibers
Found in the Caribbean
Encrusting Sponge
Phylum Ctenophora
Comb Jelly
Ctenophora
• Ctenophores (Greek for “comb-bearers”) have
eight “comb rows” of fused cilia arranged
along the sides of the animal (red rows)
– The cilia beat and propel the animal through the
water
Ctenophora
• Ctenophora are commonly known as comb
jellies and are voracious predators
– 50 species
– Most species are planktonic carnivores and
transparent which feed on zooplankton
– Light-scattering cilia and bioluminescence
– Lack stinging cells but capture prey by sticky cells
called colloblasts
– Favorite food of sea turtles
Ctenophora
• Reproduction
– Most are hermaphroditic
• Release egg and sperm in water, where sperm must
find the egg to fertilize it
• Fertilized eggs develop through larval stage that
hatches into an adult; no medusa stage
Sea gooseberry
Phylum Cnidarians
Hydras, jellyfishes, sea anemones
and corals
Cnidarians
• What is a cnidarian (ny-DAYR-ee-n)?
1. 10,000 species
2. Soft-bodied, carnivorous animals
3. Stinging tentacles arranged in circles around
their mouths
4. Simplest animals to have radial symmetry and
specialized tissues.
Cnidarians
• Specialized cells of cnidarians
1. Cnidocytes – stinging cells that are located along
their tentacles
2. Nematocyst – poison-filled, stinging structure
that contains a tightly coiled dart.
Cnidarians
• Form and Function in Cnidarians
– Simple organisms and only a few cells
thick
– Responses to the environment are
carried out by specialized cells and
tissues.
• Life cycle that includes two differentlooking stages:
1. Polyp stage
2. Medusa stage
Cnidarians
• Polyp stage
– Cylindrical body with armlike tentacles.
– Mouth points upward
– Polyps are usually sessile
Cnidarians
• Medusa Stage
– Motile
– Bell-shaped body
– Mouth on the botton
Cnidarians
• How do Cnidarians feed?
– After paralyzing its prey, cnidarian pulls the prey
through its mouth into its gastrovascular cacity