Transcript Sponges and Cnidarians

Characteristics of Animals
Sponges and Cnidarians
Invertebrates make up over 95% of all named phyla
of animals. There are over 30 different phyla.
Animals started an
explosion of evolutionary
differentiation during the
Cambrian Period. This was
possible by mutations in
Hox genes allowing for new
traits/physiology to
emerge.
Animals are placed in groups based on characteristics such as
Body Symmetry; Tissue Layers; and Development Patterns
Symmetry
• the arrangement of body structures relative to
some axis of the body
Asymmetrical
Radial
Bilaterial
Body Plan Symmetry:
Bilateral Symmetry – can be divided equally along one
plane, forms mirror-image sides
Radial Symmetry – body parts are arranged in a circle
around a central axis
Asymmetrical - no symmetry (typically found in Porifera)
Body Plan Terms
ANIMAL SYMMETRY:
The Animal Kingdom
• Multicellular
• Eukaryotic
• Heterotrophs
• Cells lack cell walls
• 95% are invertebrates
What Animals Do to Survive
• Feeding
• Response
• Respiration
• Movement
• Circulation
• Reproduction
• Excretion
Trends in Animal Evolution
• Cell specialization and levels of organization
• Early development
• Body symmetry
• Cephalization
• Body cavity formation
Phylum Porifera
• Sponges
• Have tiny openings, or pores,
over their bodies
• Sessile: they live their entire life
attached to a single spot
• They are animals! Why…?
all
SPONGES
Sponges
• Sponges are really nothing but a loose
aggregation of specialized cells.
• Of the 6,000 known spp. nearly all are
marine.
• Amazingly enough, these cells don’t
actually form organs, but do serve
similar functions, keeping the animal(s)
alive.
James Fatherree
Sponges are Animals!!!
• Multicellular
• Heterotrophic
• No cell walls
• Contain a few
specialized cells
Form and Function in Sponges
• Have nothing resembling a
mouth or gut
• Have no tissues or organ
systems
• Simple functions are carried
out by a few specialized cells
General Sponge Types
Sponges fall into several basic categories, mostly depending on
shape:
branching
tubular
Hawaiian encrusting sponge
round
encrusting
Harvested sponges
glass
boring (destructive)
Sclerosponge (CaCO3)
Ceratoporella nicholsoni
Asymmetrical Symmetry
• Have no front or back ends,
no left and right sides
• A large, cylindrical water
pump
• The body forms a wall
around a large central cavity
through which water flows
continually
Choanocytes
• Specialized cells that
use flagella to move a
steady current of water
through the sponge
• Filters several thousand
liters/day
Osculum
• A large hole at the top of
the sponge, through which
water exits
• The movement of water
provides a simple
mechanism for feeding,
respiration, circulation and
excretion
Simple Skeleton
• Spicule: a spike-shaped
structure made of
chalk-like calcium
carbonate or glasslike
silica in hard sponges
• Archaeocytes:
specialized cells that
make spicules
Feeding
• Filter feeders
• Sift microscopic
food from the water
• Particles are engulfed by
choanocytes that line the body cavity
Respiration, Circulation, & Excretion
• Rely on the movement of water through their bodies
to carry out body functions
• As water moves through the cavity:
• Oxygen dissolved in the water diffuses into the
surrounding cells
• Carbon dioxide and other wastes, diffuse into the
water and are carried away
Response
• No nervous system
• Many sponges protect
themselves by producing
toxins that make them
unpalatable or poisonous
to potential predators
Reproduction
• Sexually or asexually
• A single spore forms
both eggs and sperm;
usually at different
times
Sexual Reproduction
• Internal fertilization:
Eggs are fertilized inside
the sponge’s body
• Sperm are released from
one sponge and carried
by currents to the pores
of another sponge
Sexual reproduction
• Many sponges are
hermaphrodites, containing
male and female reproductive
capabilities, yet do not selffertilize.
•Tube sponges, such as this
Verongia archeri which is
common in Caribbean waters
use broadcast spawning to
disperse sperm and eggs in
a flurry of activity that is
often coordinated with lunar
cycles.
Asexual Reproduction
• Budding
• Gemmules: groups of
archaeocytes surrounded
by spicules
Still, if you carve ‘em up, they come back for more!!
It’s more amazing than that. If you mix groups of sponges together,
they will usually reorganize into their original groups.
Ecology of Sponges
• Ideal habitats for marine animals such as snails,
sea stars, sea cucumbers, and shrimp
• Mutually beneficial relationships with bacteria,
algae and plant-like protists
– Many are green due to these organisms living in
their tissues
Ecology of Sponges
• Attached to the seafloor and may receive
little sunlight
• Some have spicules that look like crossshaped antennae
• Like a lens or magnifying glass, they focus
and direct incoming sunlight
Phylum Cnidaria
Sea anemones, jellyfishes, coral, etc.
Cnidarians
• Phylum Cnidaria
• Hydras, jellies,
sea anemones, and corals
• Soft-bodied
• Carnivorous
• Stinging tentacles arranged in circles around their mouths
• Simplest animals to have body symmetry and specialized cells
General Cnidarian Structure
and Function
•
Centrally located mouth
•
Oral surface (mouth)
•
Aboral surface (opposite end)
•
Tentacles
•
Gut
•
Nematocysts (cnidae)!
•
Polyp and Medusa: reproductive
stages
Macrorhynchia phillipina
Beautiful, but deadly! This colonia
hydrozoan still contains cnidae.
Cnidocytes
• Stinging cells that
are located on their
tentacles
• Used for defense
and to capture prey
Nematocyst
• A poison-filled, stinging
structure that contains a
tightly coiled dart
• Found within cnidocytes
Form and Function in Cnidarians
• Only a few cells thick
• Simple body systems
• Most of their responses to the environment
are carried out by specialized cells and
tissues
Radially Symmetrical
• Central mouth
surrounded by
numerous tentacles
that extend outward
from the body
• Life cycles includes
a polyp and a
medusa stage
Body Plan
• Polyp: cylindrical
body with arm-like
tentacles; mouth
points upward
• Medusa: motile, bellshaped body; mouth
on the bottom
Feeding
• Polyps and medusas have a body wall that
surrounds an internal space: the
gastrovascular cavity
• Gastrovascular cavity: a digestive chamber
with one opening
– Food enters and wastes leave the body
Respiration, Circulation, & Excretion
• Following digestion, nutrients are usually
transported throughout the body by
diffusion
• Respire and
eliminate wastes
by diffusion
through body walls
Response
• Specialized sensory cells are used to gather
information from the environment
• Nerve net: loosely organized network of nerve cells
that together allow cnidarians to detect stimuli
– Distributed uniformly throughout the body in most species
– In some species it is concentrated around the mouth or in
rings around the body
Response
• Statocysts: groups of
sensory cells that help
determine the direction
of gravity
• Ocelli: eyespots made
of cells that detect light
Portuguese Man of War - cnidarian that floats in the
water and has long tentacles
Carukia barnesi: the baddest of the bad!
Irukandji syndrome:
A sting from this little guy can cause the following:
“It begins with a mild sting, followed by severe lower back pain,
muscle cramps in arms, legs, stomach and chest. It causes sweating,
anxiety, nausea, vomiting, headaches and palpitations, and has also
been known to cause cardiac failure.”
Movement
• Hydrostatic skeleton: a layer of circular
muscles and a layer of longitudinal muscles
that enable cnidarians to move
Reproduction: Sexually and Asexually
• Polyps can reproduce asexually by budding
• External sexual reproduction
– The sexes are separate-each individual is either
male or female
– Both egg and sperm are released into the water
CNIDARIANS
Groups of Cnidarians
• Jellies (formerly jellyfishes)
• Hydras and their relatives
• Sea anemones
• Corals
Types of Cnidaria
Cnidaria come in all shapes and sizes.
•Hydrozoans- feathey hydroids
•Siphonophores- man-o-war
Sea fan
•Scyphozoans- large jellyfish
•Anthozoan-sea anemones and coral
•Most of the animals found within Cnidaria
are all carnivores.
multiple comb jellies
Ecology of Corals
• The worldwide distribution is determined by:
– Temperature
– Water depth
– Light intensity
• Many suffer from human activity
• Coral bleaching has become common
• Global warming may add to the problem
http://video.nationalgeographic.com/video/animals/invertebratesanimals/other-invertebrates/manowar_portuguese/
Multimedia
Sponge Images and Videos http://www.junglewalk.com/video/Sponge-movie.htm
Cnidarian Images and Videos http://www.junglewalk.com/video/Coelantrate-movie.htm
General Invertebrate Movies at National Geographic
--- really good video on the portuguese man of war (under
invertebrates)
Hydra Video at http://www.schooltube.com/video/55045/Hydra