Transcript Bio11 Animals Lower Invertebrates

Lower Invertebrate:
Introduction to Animals
Whats an Animal?
 So lets think about this for a second, what really makes
an animal an animal?
 What differentiates it from a plant, fungi or bacteria?
 Are there any grey areas?
 Pollination
http://www.youtube.com/watch?v=MQiszdkOwuU&fe
ature=related
 Moving Art
http://www.youtube.com/watch?v=xQXaap6owZE&fe
ature=fvsr
Animal Characteristics
 Animals are characteristically multicellular heterotrophs
(INGESTION). This process of obtaining food requires the
most the most thought, behaviors, responses and techniques.
This makes animals more comlex.
 whose cells lack cell walls. At some point during their lives,
animals are capable of movement (motile). In the most
commonly encountered animals, this stage is the adult, although
some animals (corals) have sessile (nonmobile) adult phases and
mobile juvenile forms.
 Animals developed external or internal skeletons to provide
support, skin to prevent or lessen water loss, muscles that
allowed them to move in search of food, brains and nervous
systems for integration of stimuli, and internal digestive systems.
Phylogenetic
Tree of
Animals
Over the next three
chapters we will fly
through 9 different
phylum of animals in
increasing complexities
of body plans and life
cycles.
Body Break.
 Major divisions in the animal kingdom are based on
body plans.
 Most bodies display some level of symmetry.
 Most well known show BILATERAL SYMMETRY,
which is where you have a left and right half.
 Animals like starfish show more than one plane of
symmetry display RADIAL SYMMETRY
 Most basic show an asymmetrical body plan
Bilateral vs. Radial
Direction
 Anterior (Head),
Posterior (Anus).
 Dorsal (top),
Ventral (bottom).
 Lateral (left/right)
RADIAL:
 Oral (where
openings are
located)
 Aboral (opposite)
Radial Continued
 Lack Cephalization: Aggregation of nerve cells in one
region which would define a head.
 What are some other examples of organisms that
display radial symmetry?
Body Plans: Digestion
 Most animals have a body plan best described as a "tube-withina-tube”or ONE WAY SYSTEM.
 This plan calls for two openings: one for food to enter the body
(mouth), one for wastes to leave the body (anus). Animals with
this plan are more efficient at digesting and absorbing their food
than animals with the sac-like body plan.
 The one way system plan allows specialization of parts along the
tube.
 The sac-like body plan has only one opening for both food
intake and waste removal. Sac-like body plan animals do not
have tissue specialization or development of organs
Refresher of additional terms:
 Sessile: no movement: some aquatic animals. Passive
feeders
 Motile: ability to move and search for food.
 Gametes: are sperm (male) and ova (female)
 Gametes are haploid (N) half the genetic material, they
come together to form Zygotes which are diploid (2N)
 Asexual reproduction is rare in animals and only in
lower forms.
Vocab Continued
 Polymorphism: (many forms) possessing more than one
distinct body form (like caterpillars and butterflies) during a
life cycle. Often these alternating forms bear little resemblance
to each other.
 Metamorphism: the process where an organism changes body
structures. Many insects undergo this process.
 Broadcasters: simple aquatic animals shed gametes into the
water like plants do with pollen. Based on timing and
location.
 hermaphroditic: less motile animals, possess both male and
female reproductive organs. Do not self fertilize, released at
different times to ensure cross fertilization.
Vid break
 Tadpole Trials:
http://video.nationalgeographic.com/video/player/ani
mals/amphibians-animals/frogs-andtoads/frog_greentree_lifecycle.html
Phylum Porifera
 Sponges: simplest animals.
 Generally considered radially symmetrical or
asymmetrical
 Sessile
 Hermaphroditic
 Lacking cephalization
 Doesn’t sound like much of an animal does it?
General Info: Feeding
 Normally anchored in warm ocean water, survive by
passing water through their body cavity.
 Porifera literally means ‘pore bearing’ or having pores.
So they must play a role right?
 Pores are INCURRENT OPENINGS: passages ways
for water, gases and nutrients to enter the internal cavity.
 Openings are formed by PORE CELLS called
POROCYTES.
structure
continued
 Pore cells can regulate their size to control water flow.
Kind of like stoma in a sense.
 Water exits the sponge through the EXCURRENT
OPENING or OSCULUM.
 How does the water ‘flow?’
 COLLAR CELLS: line internal cavity and create
currents by the movement of flagella.
 Cells lining the cavity extract food and oxygen and
dispose of cellular wastes
General Info: Structure
 Internal skeleton is created
by specialized cells called:
AMOEBOCYTES.
 Secrete salts like calcium
carbonate or silicon dioxide
to form SPICULES.
 Softer ‘bath sponges’
produce SPONGEON
FIBRES which are soft and
flexible.
Sponge Skeleton

Caption: Natural sponge. Coloured
scanning electron micrograph
(SEM) showing the branching
structure of the body of a natural
sponge (phylum porifera). Sponges
are primitive aquatic animals that
filter food from the water. Their
bodies are supported by an internal
skeleton of calcium or silicon based
spicules (spines), and fibres of the
protein spongin. Magnification:
x62 when printed 10 centimetres
wide
.
Reproduction
 Sponges have a lot of reproductive options:
 They are hermaphrodites meaning the have both male
and female reproductive organs.
 Sperm are produced by Amoebocytes cells.
 No self fertilization: BROADCASTERS.
 Capable of REGENERATION: chop them off and they
grow back.
 Asexual Reproduction: GEMMULES spore like
structures formed during poor conditions. Sent out with
spent water.
Gemmules
 Gemmules are internal buds found in sponges that are
the result of asexual reproduction, and are a response to
a hostile environment.
 They are resistant to desiccation (drying out), freezing,
and anoxia (lack of oxygen) and can lie around for long
periods of time.
 These are similar to a bacterium's endospore. Gemmules
are made up of amoebocytes surrounded by a layer of
spicules and can survive conditions that would kill adult
sponges. When the environment becomes less hostile, the
gemmule resumes growing.
Final Thoughts
 Even though sponges are an animal, they lack true
tissues.
 They do however have specialized cells.
 Cells function individually without intercellular
communication.
 http://www.youtube.com/watch?v=RmPTM965-1c
 http://www.youtube.com/watch?v=BW05vMziy2o&fea
ture=related
Big Q’s
 What are the benefits and disadvantages of each type of
reproduction for a sponge?
 Broadcasting (sexual), Sessile & hermaphroditic,
Gemmules (asexual) and regeneration
 Would you classify a sponge as more of a plant or more
of an animal. Why?
 Which seedless or seed plant does it remind you of ?
What connections do they share?
Summary Table
Cnidarians
 Radial Symmetry: Members includes
 Hydra
 Jellyfish
 Portuguese man-o-war
 Sea anemones
 All united by special cells called nematocysts.
Nematocysts
 These are specialized stinging cells, and they’re really fast!
 When something in the environment (food) triggers the
barb extending from the surface of the nematocyst, the cell
collapses and shoots out a protein filament designed to
harpoon its prey.
 Filaments has a chemical anesthetic which paralyses the
food to be ingested.
 Nematocysts http://www.youtube.com/watch?v=Tp38DUjUnM&feature=related
Toxins
 Jellyfish toxins include a poorly understood array of complex
chemicals. Many have negative effects on cell membranes and cause
them to rupture. This may, for example, lead to the breaking up of red
blood cells, certainly not a desirable response to a sting. Other toxins
have disruptive effects on the action of nerve and muscle cell membranes
and impair their normal function. Throw in toxins that degrade
collagen, break down proteins and lipids, and disrupt cellular influx of
ions like calcium, and you can see why jellyfish mean business.

So behold the amazing nematocyst. Although small in stature, the
combined efforts of multitudes of these microscopic workhorses is
sufficient to subdue creatures that seemingly should have no problem
against a delicate gelatinous blob. Nematocysts are one more reason to
admire our gelatinous friends, and they are key to the success that
jellyfish and their cnidarian relatives have had in conquering all marine
habitats.
Video Break
 http://www.youtube.com/watch?v=AjM-WOeM3uA
 Jellyfish invasion
http://www.youtube.com/watch?v=eyCigZ_bsTM&feat
ure=related
Sessile Body Forms
 All cnidarians have a sac-like body
form
 Some are sessile (these are termed
POLYPS)
 Generally have an elongated body
ending in a mouth surrounded by
feeding tentacles.
 Nematocysts are found on the
tentacles.
Motile Forms
 When a cnidarian is motile,
it is termed a MEDUSA
 Very much like an inverted
polyp.
 Has a bell shaped digestive
cavity.
 Capable of changing the
shape of its bell to propel
itself through the water.
Body Walls
 Body walls of both forms are constructed out of two
tissue layers held apart by a third gel-like layer called the
MESOGLEA
 It acts as the creatures' structural support in water, as they lack
bones or cartilage, endo- or exoskeletons, or similar means of
support. Because mesoglea is a gel with such a high water
content, these creatures tend to collapse on land
 ENDODERM: inner layer specialized to digest prey
using enzymes. Surrounds the GASTROVASCULAR
CAVITY which acts as the stomach.
 ECTODERM: outer layer. Offers some protection from
environment but also contains the nematocysts.
More about the Mesoglea
 The most interesting layer…debatable.
 Random jumble of different cell types
 Some cells are nerve like since they conduct messages
 Form a NERVE NET since they do not from a
centralized system.
 Other cells in the Mesoglea become reproductive cells.
M&F, remember they’re hermaphrodites.
 These cells allow the Cnidarians to respond to their
environment. (Ever poked an anemone?)
Class: Hydrozoa
Unity of Tissue, but not
shapes
 Cnidarians: Extremely diverse in body
forms
 We’ll Discuss Three Classes of Cnidarians:
 Hydrozoans: Generally Sessile Polyps
 They are broadcasters, and reproduce
asexually by budding.
 Portuguese Man-o-War are a well
known example

http://www.youtube.com/watch?v=lem0RAVzVCM

Turtle food: http://www.youtube.com/watch?v=Iap6XiOWv0&feature=related
Portuguese Man-of-War

Although a member of the phylum Cnidaria, the Portuguese man-ofwar is not a "true" jellyfish. These animals consist of a complex
colony of individual members, including a float, modified feeding
polyps and reproductive medusae.

Physalia typically inhabit the warm waters of the tropics, subtropics
and Gulf Stream. Propelled by wind and ocean currents, they
sometimes drift into nearshore waters of South Carolina. Though
they infrequently visit our coast, swimmers should learn to identify
these highly venomous creatures.

The gas-filled float of the man-of-war is purple-blue and can reach
lengths of 10 inches. Under the float, tentacles equipped with
thousands of nematocysts hang from the feeding polyps extending as
much as 30 to 60 feet.

The man-of-war can inflict extremely painful stings. Symptoms
include severe shooting pain described as a shock-like sensation, and
intense joint and muscle pain. Pain may be accompanied by
headaches, shock, collapse, faintness, hysteria, chills, fever, nausea
and vomiting.
Class: Scyphozoa
Schyphozoans
 Motile with a a medusa body from for most of their
lives.
 Usually called Jellyfish.
 Grouped together because of their POLYMORPHIC life
cycles.
 Adults are typically male or female.
 Gametes are released into the water where fertilization
occurs.
 Resulting ZYGOTE develops into a larvae which
attaches to a surface and becomes a polyp.
Life Cycle of a Cnidarian
Class: Anthozoa
Class Anthozoa
 Primarily Sessile Polyps
 Have more complex tissues than Schyphozoans and
Hydrozoans
 Both colonial and solitary examples
 Included anemones and coral forming species.
 Not Polymorphic.
 http://www.youtube.com/watch?v=zkVoH7bfxs&feature=related
Videos

Killer Jelly

http://www.youtube.com/watch?v=NbpB5F9CcLc&feature=related

Box Jellyfish

http://www.youtube.com/watch?v=b6GuAaW9f58

Jelly Fish Life cycle: http://www.youtube.com/watch?v=Id53jmsdxfQ&feature=related

GELATO FISH! http://www.youtube.com/watch?v=ct9KyLmnu0I

Review
http://www.brsd.org/education/components/scrapbook/default.php?sectiondetailid=234
8