Sponges
Chapter 9 Section3

Live all over the world (oceans,
freshwater rivers and lakes)
Sponges
 Invertebrate animals
 No body symmetry
 Never have tissues or organs
 Looks like a hollow bag
◦Large opening at one end and
tiny pores covering the surface
 Spikes support and protect
sponges body
Sponge: Body Structure
 Eats tiny single-celled organisms
 Collar cells that line central cavity,
trap the tiny organisms
 Jelly-like cells inside sponge
digest, or break down, the food
 Sponges get oxygen from water
https://www.youtube.com/watch?v=RmPT
M965-1c
Sponge: Obtaining Food and
Oxygen

Asexually
◦ Budding: small new structures grow from the
sides on an adult sponge
◦ Buds eventually break free and begin new life

Sexually
◦ Sponges produce both sperm cells and egg
cells (do not have separate sexes)
◦ Sperm cells released in water, enter another
sponge, fertilize its eggs, larva develops
◦ Larva: immature form of an animal that looks
very different from the adult
Sponges: Reproduction
Cnidarians
Chapter 9 Section3
Jellyfish, corals, and sea anemones
 Invertebrates that have stinging cells
to capture food and protect themselves
 Take food into central body cavity

Cnidarians
 Two
different body plans
(vase and bowl)
 Radial symmetry
 Central hollow cavity
 Tentacles containing
stinging cells
Cnidarians: Body Structure
 Vase-shaped body plan is a POLYP
 Sea anemone
 Mouth opens at top
 Tentacles spread out from around
mouth
 Most are attached to underwater
surface
Body Structure:
Polyp
 Bowl-shaped
body plan is a
MEDUSA
 Jellyfish
 Adapted for a swimming life
 Mouths open downward and
tentacles trail down
Body Structure:
Medusa
 Use
stinging cells to catch animals
they eat (prey)
 Contains threadlike structure with
spines
 Uses tentacles to pull prey to
mouth
 Takes food into central body cavity
 Expels undigested food through
mouth
Obtaining Food

Unlike adult sponges, many
cnidarians move to escape danger
and to obtain food

Jellyfish?

Sea Anemones?
Movement
 Asexual
Reproduction
◦ Hydras, corals, and sea anemones
 Sexual
Reproduction
◦ Jellyfish
Reproduction
 Colony
◦ a group of many individual animals
 Stony corals and Portuguese man-ofwar
Life in a Colony
a
coral reef is built by cnidarians
 coral reefs are home to more species
of fishes and invertebrates than any
other environment on Earth
 Coral polyps produce hard, stony
skeletons around their soft
bodies
Stony Coral
 Contains
as many as 1,000
individuals that function together
as one unit
 Top: gas filled chamber, allows
colony to float
 Bottom: polyps with different
functions drift below
◦ Some catch prey and help with digestion
and reproduction
Portuguese Man-of-War