Ch17 Animals - Jocha-Biologyjocha-biology.net/handouts/gralbio/Animals.pdfMost mollusks have all organs systems present, including Circulatory and ... body divided in three main ...
Post on 18-Jun-2018
215 Views
Preview:
Transcript
Ch17_Animals
� Multicellular eukaryotes
AnimalsDomain
Domain
Domain
Kingdoms
�Nutritional mode:
�Level of organization:
�Cells
�Cells organized in tissues
�
�
� Motile
What is an animal?
Main differences with plants
�Nutritional mode: Heterotrophic (Ingestive)
�Level of organization: Multicellular
�Cells without cell wall
�Cells organized in tissues, organs, and organ systems
�Nervous tissue and muscle tissue, are unique to animals
� Bodies are held together by structural proteins such as collagen
� Motile (They move!) at least in part of their life cycle
Main differences with fungi
� Most animals:
� Are diploid (2N)
� Reproduce sexually
� Proceed through a
series of typically similar
developmental stages
Animal development
A larva (pl. larvae) is a
juvenile, young stage in the
development of animals
(examples: fish, tadpoles,
most aquatic animals)
Ch17_Animals
What is used to classify animals?
Biologists categorize animals by:
� General features of body
structure and embryologic
development
� More recently, using
genetic data
(1) Sponges are different from all
other animals because, spongeslack true tissues and organs
(1)
(2)
(2) Body symmetry.
� Radial symmetryrefers to animals that are
identical all around a
central axis, where the
mouth is located.
� Bilateral symmetry exists where there is only
one way to split the animal into equal halves.
What is used to classify animals?
(3) The presence or not of a Body cavity,
called coelom, a fluid-filled space
separating the digestive tract from the
outer body wall
(4) Most animals have three germ layers (group of cells, formed during animal
embryogenesis)…
Ch17_Animals
Really adapted to land (but not all of them are terrestrial!)
Aquatic Mostly Aquatic, Some parasites
� Most animals are aquatic!
Some facts about animals
Animals in the ocean do not
require mechanisms to deal
with rapid or extreme changes
in the environment
� Stable properties
� No risks of dehydration
� Ion contents in sea similar to
cytoplasm: osmotic balance
Why is living in the ocean
“better”?
� Insects: 65% of the animal diversity on Earth
� 95% of all animal species are invertebrates
(animals without a backbone)
�Phylum Chordata: Includes the vertebrates (Fish, Amphibians, Reptiles, Birds, Mammals)
(1) Sponges (Phylum Porifera)
� Simplest body plan: No true tissues with a
few cellular types
� No symmetry: Asymmetric
� Adults are sessile (permanently attached)
� Feeding by filtering water
� Sexual reproduction: external
fertilization and a free-swimming
larval stage
� Asexual reproduction by
fragmentation or budding is very
common
Ch17_Animals
(jelly fishes, sea anemones, corals)
Medusa (motile) Polyp (attached)
Two basic forms:
� 2) Radial symmetry
� Parts of the body
radiate from the center,
where the mouth is
located
(2) Cnidaria� 1) Evolution to true tissues with different functions
� Nervous tissue
� Reproductive tissue
� Digestive tissue
� 3) They have tentacles with stinging cells
� Incomplete digestive systemOnly a mouth/anus surrounded by tentacles
Polyp
Medusa
Reproduction
� Some show alternation of generations like in some
plants (sexual/asexual)
� Asexual reproduction produces jellyfishes or
polyps (motile), by fragmentation or budding
� Sexual reproduction produces polyps (sessile)
Stinging cells� Cnidarians are carnivores that use tentacles, armed with cnidocytes (“stinging cells”), to capture prey
Informal classification
Corals
Sea anemones
Jellyfish
Ch17_Animals
Ch 7(3) Comb jellies (Phylum Ctenophora)
� Radial symmetry like in cnidarians, but comb jellies have…
1. A radially arranged rows of ciliated plates for swimming
2. Tentacles not in whorls around the mouth,
3. Adhesive cells for food capture and the NO stinging cells
4. An aboral (top) sense organ
� Swim with eight rows of ciliary combs
� long cilia fused at the base
Continuous beating refracts light,
creating a prism-like multicolor effect
(4) Flatworms (Phylum Platyhelmithes)
� Sexual reproduction becomes dominant, though some
(e.g. planarian) reproduce asexually by fragmentation
� The first and simplest bilateral animals
� First group to show a central nervous system, that appeared
connected with bilaterally
� Better to swim or crawl in one direction!
� Allow animals to be more active when hunting
� More sophisticated behaviors are possible
� Some are free-living, many are parasites with two different types of hosts
� Parasitic flatworms are Flukes and Tapeworms
Ch17_Animals
Flukeworms: Two hosts: one vertebrate and one invertebrate
• Larva� invertebrate, Adult parasite� vertebrate
Tapeworms: Two hosts: two vertebrates.
• Larva� herbivore, Adult parasite� carnivore
Larval stage infects an
invertebrate host
Schistosomiasis: (fluke) diarrhea, liver damage, anemia, lowering of the body’s
resistance (2nd most important disease caused by parasites after malaria)
Adult parasite
infects a
vertebrate host
Blood flukes reproduce
sexually in the human host.
The fertilized eggs exit the
host in feces.
The eggs develop in water
into ciliated larvae. These
larvae infect snails, the
intermediate hosts.
Asexual reproduction
within a snail results in
another type of motile
larva, which escapes
from the snail host.
(5) Round worms (Phylum Nematoda)
� Cylindrical in shape, tapered at both ends
� Tough cuticle covers the body
� Sexual reproduction, with separate sexes
•The amount of damage is often
proportional to the number of roundworms
• Slight infestation: anemia,
• Heavy infestation: mental or physical
retardation
� Most are free-living, mostly in the sediments, being important
decomposers
� Some are harmful parasites in plants or vertebrates
Ch17_Animals
(6) Molluscs (Chitons, Snails, Slugs, Clams, Squids, Octopi)
� A Soft body, often covered with a shell, composed of one
or more plates is characteristic of this group
� Most mollusks have all organs systems present, including
Circulatory and respiratory system
� Bilaterally symmetrical, body divided in three main parts:
� A muscular foot used for movement
� A visceral mass housing most of the internal organs
� A mantle, which secretes the shell if present
� Radula is
unique to
mollusks: Ribbon
of small teeth
used to feed
� Sexual Reproduction, with
separate sexes
� A larval and free-swimming stage
(trocophore) develops in the adult form
GastropodaSnails, Slugs,
Limpets,
Abalones
BivalvesClams, Mussels, Oysters, etc
� Filter feeders (fitler the water to get the food)
� The mantle cavity of a bivalve contains gills that are
used for feeding as well as gas exchange
� Carnivores with beak-like jaws
surrounded by tentacles of their
modified foot
CephalopodaSquids, Octopuses, Nautilus
Ch17_Animals
� 2) First animals having a real body cavity (coelom), not
filled with fluid, the organs are located in the cavity
(7) Segmented worms (Phylum Annelida)
� 1) First animals with real body segmentation
� Body consists of a series of similar compartments or
segments
� Sexual reproduction, usually with separate sexes
� Most annelids have all organs systems present, including
Circulatory and respiratory system
�The three main groups of annelids are:
� Earthworms, which eat their way through soil
� Polychaetes, marine worms with segmental appendages for movement and gas exchange
� Leeches, typically free-living carnivores but with some bloodsucking forms
(8) Arthropoda
� The diversity and success of arthropods are largely due to
1) their body segmentation
2) hard exoskeleton
3) and jointed appendages
� Exoskeleton: external skeleton present in arthropods is made
of chitin (same stuff that makes cell walls in fungi!)
� Provides protection and
� Points of attachment for muscles that move appendages
� Sexual reproduction,
with separate sexes
� All arthropods have all organs systems present, including circulatory
and respiratory system
Does not grow with the individual and must be replaced
as the animal increases its size: molting
(Crustaceans, Insects, Spiders, Scorpions,
Centipedes, Millipedes, Ticks, Mites)
� Insects make 65% of animals on Earth
Ch17_Animals
Arachnids
� Live on land
� Have 4 pairs of walking legs
and a specialized pair of
feeding appendages, no
antennae
Crustaceans
� Are nearly all aquatic
� Have multiple pairs of specialized
appendages, two pairs of antennae
Millipedes and Centipedes
� Millipedes eat decaying plant matter
� Have two pairs of short legs per body segment
� Centipedes are terrestrial carnivores with poison claws
� Have one pair of short legs per body segment
Insects
� Insects live on land, freshwater, and the air!
� Have 3 pairs of walking legs, one pair of antennae
(Sea stars, Sea urchins, Sea cucumbers, Brittle
stars)(9) Echinoderms
1) Pentaradial symmetry in the adult form
� No head and tail, or left and right side present
� Body parts radiate from the center
� Bilateral symmetry during the larval stage
2) Endoskeleton, hard plates just below the skin
� Sexual reproduction, with separate
sexes
3) Also unique to echinoderms is a water vascular system and tube feet for
locomotion
� A network of hydraulic canals branching into
tube feet that function in locomotion, feeding,
and gas exchange
Ch17_Animals
(10) Chordata All chordates share during embryology…
1) Notochord: flexible rod � Gives origin to the backbone
1) 2)
2) Dorsal, hollow nerve cord � Central nervous system (brain +
spinal cord)
3)
3) Pharyngeal slits � Gills in aquatic vertebrates. Parts of the
ear, head, and neck in terrestrial ones
4)
4) Post anal tail
� Are fish that…
� Have a cranium
and rudimentary
vertebrae
� But lack jaws
and paired fins
� All ectoparasites
Lampreys
lamprey
� Chordates consists of three groups of invertebrates:
� Lancelets are bladelike animals without a cranium.
� Tunicates, or sea squirts, also lack a cranium.
� Hagfishes are eel-like forms that have a cranium.
� All other chordates are vertebrates, which show segmentation
in the backbone and muscles
hagfish
Hagfish
slime
Ch17_Animals
� Gills for gas exchange
� External fertilization
� Soft shelled eggs
Fish� The two main groups are
cartilaginous and bony fish
� Have jaws and paired fins
� Are the most diverse group
of vertebrates
Amphibians� Includes frogs, toads, salamanders
� Were the first tetrapods (vertebrates with 4 legs)
� Wet skin (not adapted to live in dry environments)
� Lungs (not fully functional) and skin for gas exchange
� External fertilization
� Soft shelled eggs
� Still need to back to
the water for reproductionTadpole (larva)
� Waterproof skin
� Internal fertilization
� Hard shelled and amniotic eggs� Have mammary glands that produce milk,
which nourishes the young
� Have hair
� Most develop the embryo inside the mother
Reptiles� Are the first vertebrates to be
fully adapted to land
Birds� Are very modified reptiles
that have in addition unique
adaptations for flying
� Hollow bones
� Feathers
� Forelimbs modified as wings
Mammals
Ch17_Animals
The Amniotic Egg
� Is the sac in which the fetus
develops in amniotes. It is a
tough but thin transparent pair
of membranes, which hold a
developing embryo until
shortly before birth
Ch.21
� The placenta, which helps in nutrition and gas
exchange, includes the…
� The amniotic sac, that has the amniotic fluid
and the embryo
� Blood from the embryo travels to the placenta
through arteries of the umbilical cord and returns
via the umbilical vein
In mammals…
(Water-filled membrane, protection and moisture)
AMNION
In reptiles and birds…
Skeleton
Many animals have some type of
support system or skeleton. Skeletons
serve as:
� Protects the animal
� Provides points of attachment
for muscles
Does not grow with the individual
and must be replaced as the animal
increases its size
Endoskeleton:
internal skeleton
present in
vertebrates and
some
echinoderms
Exoskeleton: external skeleton
present in roundworms and
arthropods
Chitin � insects, spiders,
scorpions, centipedes,
millipedes
Add calcium! � crustaceans
Ch17_Animals
Temperature regulation
Ectotherms:
Animals cannot regulate the body temperature
Regulate their temperature by moving
from one place to another:
• all others
Have internal temperature-regulating
mechanisms:
• birds and mammals
• Able to adapt to any environment
• But with a very high metabolism
(energy use)
Homeotherms / Endotherms:
• Animals that maintain a constant
body temperature, generally
higher than the environmental
temperature
top related