Transcript Genus - Blue Valley Schools

Origins of the multicellular animal
Porifera
Cnidaria
How did animals transition from Unicellular to Multicellular?
Two possibilities:
1.
: Cells stay together as they divide,
forming a colony. Colony cells begin to differentiate
and become specialized.
.
2.
: (Large multinucleate cell)
Plasma membranes begin to form, dividing up the nuclei
as the new cells begin to differentiate/specialize.
Did all existing animals evolve from ONE, TWO, or
Several ancestors?
: All animals derived from a single ancestor
-Process of mitosis
-Proteins used in flagellate/ciliate movement.
-Nucleotides
: All animals derived from two separate
ancestral lines.
: All animals derived from multiple
ancestral lines.
: (about 520 mya) A simultaneous
development of most major animal phylum over a period
of several million years.
•This makes monophyletic more difficult to accept.
(Sponge)
(Pore + to bear)
:
• Sponge are marine and
freshwater organisms.
• 15,000 or so species of sponges,
only about 100 live in fresh
water; the rest are marine.
• Adult sponge are
(attached to the substrate).
:
• Sponge show
symmetry.
• Multicellular organisms but no
tissue level organization.
• Sponge are
,
pulling water through their
bodies and collecting
mostly microscopic
organisms that pass through.
:
1.
: Exterior cells. Can contract or expand
to control water flow.
: Create openings to interior of sponge.
2.
: Inner cells. Jelly-like layer of cells.
: Amoeboid and mobile cells.
• Reproduction
• Create skeletal component
• Transport food
3.
: Flagellated cells with collars.
• Flagella creates current to move water through
sponge.
• Collar acts as net, catching and absorbing food.
Structure:
: Skeletal
structures act to
support sponge.
• Created by Mesenchyme
(or Amoeboid cells) of
calcium carbonate or
silica.
• Can be used to help
identify sponge.
2.
: Soft protein fibers made of
collagen.
Natural bath sponges are
spongin.
:
Simplest and least common.
(Vaselike)
Folded sponge wall.
Extensively branched canal system.
Porifera feed on small particles in the water.
• Protists
• Bacteria
• DOM
Most sponges feed on microbes,
few sponges are carniverous.
Genus: Chondrocladia
capture most food particles in their collar
and transfer particle to food vacuole.
then receive food vacuole, digest food
and transport nutrients around organism.
• Sponge also feed through
absorption.
cells
that line the incurrent
canal use endocytosis.
• Sponges have no nerves or muscles, but the
individual cells can sense and react to changes in the
environment.
• Chemical signals are sent from one cell to another
allowing cells to communicate.
Sexual Reproduction
male and female reproductive structures
on same organism.
1. Choanocytes go through meiosis, converting into
flagellated sperm cells or eggs.
2. Sperm and eggs are never produced at the same
time in an organism
3. Eggs stay internal
4. Sperm exit through the osculum and are eventually
taken
in by another sponge of the same species.
Zygote
Flagellated Larva
(mobile stage)
Early Adult
:
: Spicule encased amoeboid cell released when adult
stage dies.
.
Domain
Kingdom
Phylum
Eukaryota
Animalia
Porifera
Order
Family
Genus
Species
~400 species
-Evidence suggests first to diverge from ancestry
-Usually vase shaped (Ascon)
-Spicules calcium carbonate
Calcareous
Lime/Chalky
tri/tetraxons
-All three body forms
-Marine
(Ascon)
Domain
Kingdom
Phylum
Eukaryota
Animalia
Porifera
Order
Family
Genus
Species
-Glass sponges
-Usually found at depths of 3000ft
-Sycon or Leucon
-Spicules made of Silica
-Some INDIVIDUAL organisms thought
to be over 15,000 years old
Domain
Kingdom
Phylum
Eukaryota
Animalia
Porifera
Order
Family
Genus
Species
-Marine or Freshwater
-Leucon body form
-Largest sponge Class
~8000 species
-Mostly Spongin structure
-Freshwater types produce
gemmules
Jellyfish, Anemonies, Coral
(to have nettle)
Over 9000 species
Most species of Cnidaria are marine. A few are
freshwater dwelling.
: Radial
Radial symmetry is
advantageous to sedentary
animals because sensory
receptors are evenly distributed
around the animal.
:
: Two tissue layers each with a special
function.
: Outer layer of
body wall.
: Gastrodermis,
or inner layer of body
wall.
All cells of the ectoderm differentiate into several
different cell types.
All cells of the endoderm differentiate into several
different cell types.
: Non-cellular,
jelly-like layer between
The ectoderm and the
endoderm.
:
Cell Types
: Cells of the endoderm that help
digest food.
: Cells in either tissue layer that produce
nematocysts.
-Attachment
-Defense
-Feeding
: Fluid filled structure inside the cnidocyte.
Coiled and compressed.
Point or tube at terminal end.
-Can be toxin filled
to stun prey
-May have sticky
secretions to anchor
to substrate.
:
-
:
Body forms alternate between generations
: Anchored to substrate, gathers food with
mouth end.
: Free-swimming, central mouth opening
facing downward.
:
-All food, waste, and gamates enter and exit the mouth
opening.
-Mouth opening empties into the
.
: Cells that line the GVC that digest food.
Derived from the endodermis.
Small crustaceans are a majority of the cnidarians diet.
-Nematocysts entangle the prey
and paralyze them.
-Tentacles shorten, pulling the
prey to the mouth.
-Once in GVC, digestive enzymes
are released. Food turns to mush.
-Specialized cells absorb food
particles.
:
body fluids confined
to a central cavity.
-Contraction against the fluid aids in movement.
:
: Summersault, inchworm, glide along
base, walk on tentacles.
: Swimming and floating.
-Water currents control horizontal moves
-Contractions control vertical moves.
: Male and female gametes are produced
On separate organisms.
Gametes are released by the Gonads.
Reproductive cycle:
Fertilization  Blastula 
(ciliated larva)
Attach to substrate  Polyp  Budding  Medusa
Domain
Kingdom
Phylum
Eukaryota
Animalia
Cnidaria
Order
Family
Genus
Species
•Mostly Marine
•Few freshwater examples that live
attached to aquatic freshwater
plants.
•Show alternation of generations.
1. Nematocysts in Epidermis only
2. Gametes are released externally. (budding)
3. Mesoglea never contains amoeboid cells.
Colonial cnidaria with
individual specialization.
•Feeding polyps
•Asexual reproductive polyp
•Medusa reproduces
sexually.
•Freshwater organism
•Lacks Medusa stage
•Sexual and asexual
reproduction both in
polyp stage.
(forms external ovaries/testies)
Domain
Kingdom
Phylum
Eukaryota
Animalia
Cnidaria
Order
Family
Genus
Species
•“True Jellyfish”
•All Marine
•Majority of lifespan is medusa
•Nematocysts in both tissue layers
•Gametes internal
)
: Sensory receptor
Photoreceptor: Light
Statocyst:
Gravity
Domain
Kingdom
Phylum
Eukaryota
Animalia
Cnidaria
Order
Family
Genus
Species
•
•
•
•
“Box Jelly”
Cube shaped
Tentacles at corners
Strong nematocysts
Sea Wasp 
Domain
Kingdom
Phylum
Eukaryota
Animalia
Cnidaria
Order
Family
Genus
Species
Marine organisms
Solitary: Anemones
Colonial: Coral
Anthozoa Polyps:
1. Have a Pharynx separating the mouth and the GVC
2. Nematocytes and Gonads located IN the GVC
3. Mesoglea may contain amoeboid cells
• Solitary animals, attach to substrate
is the attachment point
• Mouth surrounded by large tentacles
Contracting cell types
Longitudinal: Contractions can expel water
and cause tentacles to retract.
Circular: Contractions help with movement.
Nutrition
Small invertebrates and fish
: A piece of the pedal disc may break away and can
grow into a new organism. (Pedal Laceration)
Dioecious
Fertilization  Planula  Adult
:
• Produce Calcium Carbonate
exoskeleton
• Sexual reproduction is
external
• Asexual: Forms a new
member of the colony
Domain
Kingdom
Phylum
Class
Class
Class
Phylum
Class
Class
Class
Class
Eukaryota
Animalia
Porifera
Calcarea
Hexactinellida
Demospomgiae
Cnidaria
Hydrozoa
Scyphozoa
Cubozoa
Anthozoa