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Animals
What is an animal?
• Multicellular, eukaryotic, heterotrophic, nonphotosynthetic, without cell walls
• Either vertebrates or invertebrates
• Containing specialized cells that have a
division of labor in a organism. Animals have
specialized cells to enable them to sense and
seek out food and mates, and allow them to
identify and protect themselves from predators.
Seven Survival Methods
• Feeding - herbivores, carnivores, parasites, filter
feeders, detrivores
• Respiration-exchange of gases
• Internal transport - circulatory system; open or
closed
• Excretion - removal of waste
• Response - use of nerve cells to respond
• Movement-use of muscles & skeleton
• Reproduction-sexual or asexual;live young or
eggs
Stages of Development
• Most animals develop from a fertilized egg cell called a zygote. In
animals, fertilization may be internal (inside the body) or external
(outside the body).
• After fertilization, the zygote of different animal species all have
similar, genetically determined stages of development.
• Fertilization occurs when a sperm cell penetrates the egg cell,
forming a new cell called a zygote.
• The zygote divides by mitosis and cell division to form two cells in a
process called cleavage.
• Once cell division has begun, the organism is known as an embryo.
• First layer – blastula, second layer – gastrula
– Endoderm – inner lining
– Ectoderm – outer lining
– Mesoderm – middle lining
What is symmetry?
• To have a consistent overall pattern of
structure.
• Three types
– Radial - similar parts that branch out in all
directions from a central line
– Bilateral - two similar halves on either side of a
central line
– Asymmetrical – having no symmetry
What are the body regions?
• Based on normal orientation of the
organism.
–
–
–
–
Anterior - head region
Posterior - tail region
Dorsal - top or back region
Ventral - bottom or stomach region
What is cephalization?
• The gathering of sensory organs and brain
structures in the anterior region.
• Organisms with cephalization will always have
bilateral symmetry.
Animal Protection & Support
• Exoskeleton – hard outer covering made of chitin.
• Endoskeleton – made of calcium carbonate, cartilage or bone.
• Invertebrate – animals without backbones but w/exoskeletons
• Vertebrate – animals with backbones.
Kingdom Animalia
Phylum Porifera
Sponges
Sponges
• No mouth, stomach or other
organs
• sessile -(not moving) as
adults, mobile -early stage
• no symmetry
• smallest - 1 cm long
• largest - 2 m wide
• filter feeders
• reproduce both ways
• hermaphrodites - containing
both sexes
Parts of the sponge
• Epithelia-like cells – thin and flat responding to touch.
• Collar cells – lining the interior of the sponge. Each
cell has a flagellum used to draw water into sponge.
• Pore cells – surrounds each pore that allow water to
carry food and oxygen into the body.
• Osculum- large opening where water and waste is
pumped out.
• Spicules - hard particles made of CaCO3 or SiO2 used
for support.
• Amebocytes- b/t the two layers that aid in bringing in
food, reproduction and making spicules.
Kingdom Animalia
Phylum Cnidaria
Hydra, Jellyfish, Coral
What are the body shapes & parts?
• Two body shapes
– polyp - specialized sessile shape
– medusa - specialized bell shape for swimming
• Parts
– epidermis - outer layer
– mesoglea - middle layer
– gastrodermis - “stomach skin” inner layer
More Parts
• Gastrovascular cavity - the “stomach” or
hollow gut surrounded by tentacles.
• The tentacles contain nematocysts which are
stinging structures used for defense and
capturing food.
• This group is considered to be carnivores with
radial symmetry.
• Both sexual and asexual reproduction
• Simple nervous system w/out a brain using a
nerve net to conduct impulses.
Classes of Cnidarians
• Class Hydrozoa – hydras
and siphonophores
• Mostly marine polyp
colonies
• reproduce both ways
• Hermaphrodites
• examples include:
– Obelia, Portuguese man-ofwar
Photo credited by key-biscayne.com
Eleutheria dichotoma
Ectopleura larynx
Gonothyraea loveni
Class Scyphozoa
•
•
•
•
Jellyfish
Medusa is dominant stage
Everywhere in oceans
Only class of totally
venomous organisms
• Most are harmless but some
can cause death.
• Examples: Australian box
jellyfish, moon jellyfish, Lion
mane jellyfish
Body plans of the Scyphozoans
Class Anthozoa
• Sea anemones & corals.
• Polyps is the only form
and they feed on passing
prey.
• Corals are made of
calcium carbonate live
in shallow depths make
coral reefs.
• Tropical and
Subtropical waters
Class Ctenophora
• “Comb jellies”
• Beat cilia to move
• Secrete sticky mucus
to attack prey
• Most are
hermaphroditic
• Unique feature bioluminescent
All Material Copyright: © Wim van Egmond
Kingdom Animalia
Phylum Platyhelminthes
Flatworms
Flatworm Make-up
• Simplest animal with bilateral symmetry exhibiting
cephalization
• Range from 1 mm to several meters
• Found in marine, freshwater & moist land habitats
• No circulatory or respiratory system
• One opening for food in and out
• Contain a gastrovascular cavity
• Eyespots – used to sense intensity & direction of light
• Pharynx – used to ingest food
• Flame cells – collects excess water & removes it
• Proglottids – body sections: old ones near
Class Turbellaria
• Mostly free-living marine
• Move by swimming w/a wave-like motion or a
mucus and cilia
• Feed as scavengers, carnivores
• Reproduction – sexually as hermaphrodites that
fertilize each other internally and asexually through
regeneration.
• Contain eyespots, pharynx, flame cells & simplistic
nervous system with ganglia.
• Most common type is the planarian “cross-eyed”
Marine Flatworms
Pictures of Planarians
“Cross-eyed” worm
Class Cestoda
• Tapeworms – humans house seven different species. Lives
in the intestines as parasites
• Contains a scolex “head” with suckers & hooks for
attaching & proglottids which have muscles, nerve cells, &
reproductive cells. Each proglottid can contain 100,000
eggs.
• No eyespots, mouth, gastrovascular cavity, or digestive
organs.
• Almost all are hermaphroditic.
• Can grow up to 10 m or 33 ft long.
• Beef, pork and other types.
Beef Tapeworms
Life cycle - eggs left
behind by infected
organism. Ingested by
cow(intermediate), cow
slaughtered, people eat
undercooked meat, eggs
hatch and infect human
(primary), eggs exit in
feces.
http://www.merck.com
Class Trematoda
• Parasitic &
hermaphroditic
• Blood flukeSchistosoma – causes
schistosomiasis. See life
cycle on Pg. 710
• Brown fluke – N.
America causes
swimmer’s itch
• Liver fluke
Phylum Nematoda
•
•
•
•
•
Roundworms
Digestive tract w/two openings
Most are separate sexes
Protective layer - cuticle
Most free-living, some parasitic living in
soil, animals, fresh and salt water.
• Humans play host to 50 types
Types of Roundworms
• Ascaris - intestines of
pigs, horses, humans.
• Lay about 200,000 eggs
• Hookworms - burrow
into foot through blood
to the intestine. 400
million people infected
worldwide.
Types of Roundworms
• Trichinella - causes
trichinosis. Humans,
pigs, mammals. Eating
undercooked pork.
• Pinworms - most
common in US
• Filarial worms -tropical
countries. Causes
elephantiasis
Pinworm
Original image from Oklahoma State University, College of Veterinary Medicine.)
Phylum Rotifera
• Rotifers
• transparent, freeliving, fresh water
• uses flame cells
• bilateral symmetry
w/cephalization
• two eyespots
all material © Wim van Egmond