Transcript 31 - Westgate Mennonite Collegiate

Chapter 31: Animals Part II
Phylum Echinodermata
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Echinoderms:
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Radial symmetry as adults
Endoskeleton of calcium-rich plates
Spiny skin
Unique water vascular system with tube feet
Able to regenerate lost body parts
Include sea stars, sea cucumbers, sea lilies,
brittle stars, sea urchin, sand dollars (see.
p.646 for pictures)
Phylum Echinodermata
Phylum Chordata
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4 Chordate Characteristics: (have all 4 at
some point in lifecycle)
◦ Segmented with a notochord (a dorsal
supporting rod)
◦ Dorsal tubular nerve cord
◦ Pharyngeal pouches at some point of
development (become gills in fish, auditory
tubes in mammals)
◦ Post anal tail at some point in life cycle
Phylum Chordata
Phylum Chordata
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Subphylum Unicordata
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Sessile adult
Encased in a tunic
Lacks notochord and nerve cord as adult
E.g. tunicates
Phylum Chordata
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Subphylum Cephalochordata:
◦ Retains the four chordate characteristics as
adults
◦ Obvious segmentation throughout body
◦ E.g. Lancelets
Phylum Chordata
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Subphylum Vertebrata:
◦ Notochord is replaced by the vertebral
column
◦ E.g. fishes, amphibians, reptiles (includes birds),
mammals
Vertebrate Intro
Have all 4 chordate characteristics at
some point of development
 Embryonic notochord generally replaced
by vertebral column
 Generally a high level of cephalization
(brain and nervous system) with complex
sense organs
 Closed circulatory system
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Vertebrate Intro (cont’d)
Jaw evolution allowed for easier predation
 Strong endoskeleton allows for large
terrestrial organisms
 Complete digestive tract
 Generally, sexes are separate (not
hermaphrodites)
 Sexual reproduction typical
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Vertebrate Intro (cont’d)
Evolution of amnion (extraembryonic
membrane that encloses a fluid filled sac)
 Some lay shelled eggs
 Others are placental (e.g. mammals) and
development of offspring occurs in female
uterus
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Fishes
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Evolutionary development:
(from least to most evolved)
1. Jawless fishes (superclass Agnatha)
a)
b)
c)
d)
e)
About 63 species
Cylindrical
Up to 1 meter long
Include hagfish and lampreys
Some are parasitic
Fishes (cont’d)
2. Cartilaginous fishes (class Chondrichthyes)
a) About 850 species
b) Include rays, sharks and skates
c) Have jaws (adapted gill arches – structure that
supports gills)
d) Skeletons made of cartilage (not bone)
e) Well-developed senses make good predators:
a)
b)
c)
Ability to sense electric currents in water
Have lateral line system that allows them to sense
pressure changes in water from movement nearby
Keen sense of smell
Fishes (cont’d)
3. Bony fishes (class Osteichthyes)
a) About 20 000 species
b) Most diverse class of all vertebrates
c) Types of bony fishes:
I.
Ray-finned fishes
i.
Include fish we commonly eat: trout, cod, salmon
ii. Have a pair of fins with thin bodies
iii. Often have a swim-bladder, which regulates buoyancy
iv. Water passes into mouth and out through gill slits:
oxygen is absorbs and carbon dioxide given off
v. Heart is simple pump with two chambers (one
atrium and one ventricle)
Fishes (cont’d)
II.
Lobe-finned fishes
i.
Evolved into amphibians
ii. Had fleshy appendages that were adapted to limbs
for terrestrial life
iii. Had a lung used for respiration
iv. E.g. coelacanth, though extinct 20 000 years ago was
discovered off the coasts of Eastern Africa
Fishes (Cont’d)
Amphibians
Beginnings of adaptations to terrestrial life
 Amphibian = land and water (live parts of
life cycle in both
 Some have lungs, other respire through
skin
 Heart is 3 chambered (one ventricle)
 Ectothermic (cold-blooded – externally
regulated body temperature)
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Amphibians
Reptiles
Include turtles, alligators, snakes, lizards, and
birds
 Development of amniotic egg allowed for
non-aquatic embryo development
 3 chambered heart (e.g. snakes) and 4
chambered hearts (e.g. birds, crocodiles)
present. (Fishes have only 2 chambers.)
 4 chambers
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◦ allows for more efficient metabolism
◦ Endothermic (self-regulating body temperature)
Reptiles
Mammals
Major development: hair and mammary
glands
 Includes:
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◦ Monotremes
 Lay hard-shelled eggs like birds
 E.g. spiny anteater and duckbilled platypus
◦ Marsupials
 Begin development inside female’s body and mature
in pouch
 E.g. kangaroos, opossum
Mammals
Mammals
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Placental Mammals
 Majority of mammals living today
 Internal in utero development of embryo
 Placenta is site of exchange between fetal
and maternal blood
 Adapted fully to life on land (exception:
dolphins and whales)
Mammals
Highly developed brain
 4 chambered hears
 Includes our order: primates.
 Adapted to arboreal life (life in trees)
 Many have opposable thumb and five digits
on each of their four limbs
 Larger and more complex brain
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Mammals
Summary
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Evolutionary adaptations: (in order of least
to most advanced: (see p.649 for examples)
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Ancestral notochord
Vertebrae
Jaws
Bony skeleton
Lungs
Limbs
Amniotic egg
Mammary gland