invertebrates. animal characteristics animals are the most physically diverse kingdom of organisms....
TRANSCRIPT
Invertebrates
Animal Characteristics• Animals are the most physically
diverse kingdom of organisms.• They range in size from twice the
length of a school bus to microscopic
4 Major Characteristics of Animals• 1. They are multi-cellular heterotrophs• 2. Animal cells are supported by collagen
– three-strandedprotein
– found in bone,skin, ligaments,fingernails,and hair
• 3. Animals are diploid and reproduce sexually
Diploid cells have two copies of each chromosome: one copy from the mother and one from the father
• 4. Animals have Hox genes– Homeotic genes control early development.– Hox genes determine the position of cells
differentiation.– A Hox gene mutation leads to the development of
a body structure in the wrong position and/or animal diversity
Animal Diversity• Animals are grouped into vertebrates (animal
with backbones) or invertebrates (animals without backbones)
• More than 95% of all animal species are invertebrates- an animal without a backbone
Animals are grouped according to these 3 criteria
• 1. Body Plan• 2. Tissue Layers• 3. Developmental Patterns
blood vessels
brain
hearts
muscle
segmentnerve cord
mouth
digestive track
gastrovascular cavity
mouth
mesoglea
oral arms
tentacles
There are two types of Body Plans
Bilateral Symmetry Body divides equally along one
plane
Radial Symmetry• Body arranged in a circle
around a central axis
Tissue LayersBilateral
• Have 3 distinct layers: ectoderm, endoderm, and mesoderm– Ecto- develops into skin,
the brain, and nervous system
– Endo- lines the “gut”– Meso- develops into
internal organs
Radial
• Have two distinct layers: ectoderm and endoderm
Animals are separated into two major groups
• Protostome- mouth develops before anus
• Deuterostome- anus develops before mouth
Invertebrate Diversity
Sponges
• Sponges are the most primitive animals on Earth.
• Sponges share common characteristics.– Sessile- attached to floor
of ocean (do not move)– reproduce both sexually
and asexually – filter feeders- strain food
particles from water
Sponges have three types of cells1. Pinacocytes- form
the sponges outer layer
2. Choanocytes- pull water into sponge and help trap food
3. Ameobocytes- absorb and digest food particles
osculum
choanocyte
amoebocyte
pinacocyte
pore
spicule
Sponge Video
Cnidarians (Jellyfish)• Cnidarians come in two body forms
– Polyp- cylindrical tubes with mouth and tentacles facing upward
– Medusa- umbrella-shaped, with mouth and tentacles on the underside
Cnidarian Video
Cnidarian Anatomy• Cnidarians are made up of two tissue layers
separated by mesoglea• The outer tissue layer has three cell types.
– contracting cells – covers the surface of the cnidarian
– nerve cells- sends information around animal to coordinate movement
– cnidocytes (which contain nematocysts)- “stinging cells” used for defense and capturing of prey
barbscoiled nematocyst
dischargednematocyst
Flatworms• Flatworms have a solid body and incomplete
or absent gut. • They have no circulatory system
head
pharynx
mouth
sucker
eyespotreproductivesystem
gut cavity
3 classes of Flatworms
• Planarians- free-living non parasites• Flukes – parasites which can infect humans and cause
serious disease (schistosomiasis) – Infects 200 million people in Africa and Southeast Asia– Contracted by wading in or drinking contaminated
water• Tapeworms- are parasites that live in vertebrates gut
– Use suckers or hooks to attach to host– Absorb nutrients from the food the host eats
Tapeworm Video
Mollusks
• Mollusks have a complete digestive tract with two openings – a mouth and an anus
• Coelom ( fluid filled body cavity)is present– Except in flatworms
• Mollusks have all three tissue layers• Have a brain and spinal cord (cephalization)• Have a circulatory system
– Primitive species (open) such as bivalves– Advanced species (closed) such as octopus and squid
Mollusks Anatomy
• Mollusks share at least one of three features. – radula : file like teeth used to obtain food– mantle : area of tissue covering the internal
organs, sometime secrete a hard outer shell for protection
– ctenidia: flat gills found in the mantle
intestine
stomach
digestive gland
footanus
salivary glandcrop mouth
radula
mantle
mantle cavityheart
• Most mollusks are classified into three classes. – Gastropods: includes snails, abalone, and slugs
they are found on both land and water
– Bivalves (Pelecypods): clams, oysters, mussels, and scallops. Protected by two hinged shells
– Cephalopods: squid, octopus, nautiluses, and cuttlefish. Most advanced mollusks
and are predators
Mollusk Video #1
Mollusk Video
• http://my.hrw.com/content/hmof/science/high_school_sci/tx/gr9-12/hmd_bio_9780544073890_/dlo/biologyvideoclips/index.html?vid=92
Annelids• Three groups of Annelids
– earthworms, leeches, and marine worms• They are characterized by having
segmentation: division of the organism into repeated sections
• They have a coelom and all three tissue layers• They breathe by diffusing oxygen through
their skin• They are hermaphroditic so they can
reproduce either sexually or asexually
Annelid Video
• http://my.hrw.com/content/hmof/science/high_school_sci/tx/gr9-12/hmd_bio_9780544073890_/dlo/biologyvideoclips/index.html?vid=91
Roundworms• Roundworms have bilateral
symmetry and shed their outer skeleton to grow.
• Roundworms are protostomes with bilateral symmetry
brain
cuticle
pharynx intestine
anus
tail
• Roundworms have a psuedocoelom (“false” not complete body cavity)
• They do not have a respiratory or circulatory system