Download Invertebrates and Chordates

Unikont Diversity III: Invertebrates and Chordates Ch. 33, 34
I.
Invertebrates
1. Animals that lack a backbone
2. Account for >95% of known animal species
3. Morphologically diverse, found in almost every habitat on Earth
A. Phylum Porifera: least complex, sac-like body with tiny holes, multicellular
specialized cells but no true tissues or organs, asymmetric 2 halves of body, lack
true tissues and organs
a. Structure: typical simple sponge
1. Osculum = open end
2. Spondocoel: central cavity  acts as a passage for water.
a. Sponges are filter feeders
b. Not a digestive chamber
3. Choanocytes (collar cells)
a. Similar to choanoflagellates (protists)
b. Flagellated cells
c. Have a collar of microvilli
d. Line spongocoel
e. Ingest bacteria and tiny food particles
B. Phylum Cnidaria: mostly marine carnivores (ex. Jellyfish, coral, etc)
1. Characteristics
a. Radial symmetry
b. Diploblastic
2. Body structure
a. Hollow sac with mouth and tentacles at one end
b. Mouth: only opening in body  ingest food and expel wastes
c. Gastrovascular cavity: digestive compartment with single opening
d. Cnidocytes: specialized cells in tentacles  function in defense/prey
capture
C. Lophotrochozoa clade: most bilaterians, based on molec data
1. Characteristics
a. Bilaterally symmetrical
b. Triploplasts
2. Common features
a. Lophophore: crown of ciliated tentacles around mouth  feeding
structure
b. Trochophore larval  stage of development
3. Five Phyla
a. Platyhelminthes
b. Rotifer
c. Lphophorates = ectoprocts + brachiopods
d. Mollusca
e. Annelida
4. Platyhelminthes
a. Dorsoventrally flattened, acoelomate, free living sp (planarians),
parasitic sp (tapeworms)
5. Rotifers
a.
b.
c.
d.
Freshwater/marine/damp soil, pseudocoelomates
Alimentary canal complete digestive tract, tube with 2 openings
Crown of cilia at head  draws vortex of water into the mouth
Trophi  jaws that grind up food (microorganisms suspended in
water)
6. Lophophorates: ectoprocts and brachiopods
a. Marine/freshwater, lophophore, coelmates
7. Mollusca
a. Snails, slugs, oysters, clams, squid, octopus
b. Soft body: most covered by dorsal shell of calcium carbonate
c. Has a radula = belt of teeth in mouth area
d. Coelomates with 3 min body parts
i. Foot: muscular, for locomotion, may be modified into
tentacles
ii. Visceral mass: contains viscera, internal organs
iii. Mantle: thin sheet of tissue covering visceral mass. Contains
glands  secrete shell if present
e. 3 major clades
i. Gastropoda: mostly marine, also freshwater; damp soil;
snails with shell, slugs with no shell
ii. Bivalvia: shell = 2 parts, hinged, secreted by mantle; no
radula bc suspension feeders
iii. Cephalopoda: squid, octopus, marine. Predatory, mouth has
radula + 2 strong beaks. Foot modified to form tentacles
8. Annelida
a. Major characteristic: segmentation  body wall, coelom and many
internal organs are divided into segments/ digestive tract not
segmented
b. Marine, freshwater, damp soil
D. Ecdysozoans: covered by tough coat called a cuticle, ecdysis is when cuticle is shed
or molted
a. Phylum Nematoda
i. Roundworms: cylindrical with tapered ends
ii. Aquatic, soil, parasitic
iii. Cuticle covers body
iv. Pseydocoelomates
v. No circulatory system
b. Phylum Arthropods
i. Segmented body: head, thorax (legs and wings), abdomen
(posterior segment)
ii. Jointed appendages: swim walk sensory structures
iii. Jointed exoskeleton (chitin and protein) that covers entire body
1. Advantage: protection, limits loss of water, muscles
attachment
2. Disadvantage: limits growth, must molt to grow
E. Deuterostomes
a. Characteristics
i. Radial and indeterminate cleavage + blastopore becomes anus
ii. Other animals also share these dev characteristics
iii. Deutrostomes are defined primarily by dna similarities
b. Echinodermata (sea stars) and chordata (invertebrates and vertebrates)
c. Echinodermata
i. Larvae: bilateral symmetry
ii. Adults: 5 part body org symmetry
iii. Endoskeleton of CaCO3, spines project out through epidermis
iv. Water vascular system: network of fluid filled canals and chambers.
Functions in feeding and gas exchange
II.
Chordates
A. All chordates
1. Derived characters of all chordates
2. Notochord: firm but flexible longitudinal supporting rod  internal skeleton in
all chordate embryos and in adults of some forerunner of backbone  located
between gut and nerve cord
3. Dorsal, hollow nerve cord: other animals have solid nerve cords usually ventrally
located  develops into central nervous system
4. Pharyngeal slits or clefts: ancestors were probably suspension feeders
5. Muscular, post-anal tail: appendage  extends posterior beyond anus
6. Lancelets: cephalochordate: most basal group of chordates, invertebrates,
marine susp feeders
7. Tunicates (Urochordata): invertebrates, marine susp feeders, only one set of
Hox genes
B. Vertebrates
1. Derived characters
1. Chordate characters most evident in embryo
2. Adult: backbone of bone or cartilage replaces notochord 
vertebraeenclosing a spinal cord
3. 2 or more sets of hox genes11111
4. 111111111111111111111111
C. Gnathostomes: jaw mouth
1. Derived characters
1. Hinged jaws, advantage  can grasp and hold on to prey while eating
2. 4 sets of Hox genes
2. Basal clades
1. Chondrichthyes
2. Aquatic, cartilaginous fishes
3. Skeleton is cartilage, flexible
D. Osteichthyans
1. Derived characters
1. Bony skeleton: hard matrix of calcium phosphate
2. Lungs: arose in early lineages to supplement gas exchange by gills
2. Basal clades
1. Actinopterygii
2. Aquatic, ray finned fishes  fins supported by bony rays
E. Lobe-fins
1. Derived characters …
1. Muscular fins or limbs
2. Basal clades
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F. Tetrapods
1. Derived character
1. 4 limbs, support weight on land
2. Neck  allows head to move around
3. Fused pelvic girdle- efficient struc for transmitting forces thru body
2. Basal clades
1. Amphibian – first tetrapods
2. Eggs must be laid in water or damp, bc larvae is aquatic
3. Thin, moist skin. Terrestrial but associated with damp areas
G. Amniotes
1. Derived charact
1. Amniotic egg- has an amnion, membrane that forms fluid filled sac
around embryo, terrestrial egg
a. Important bc allows animals to complete life cycles on land
2. Rib cage ventilation – more efficient than breathing thru skin and
conserves water
2. Clades: reptilian (and birds), mammalia
3. Reptilian
1. Hard, dry scales containing the protein keratin, protects from
desiccation and abrasion
2. Shelled eggs laid on land
3. Lizards n snakes: cold blooded
4. Birds: tetrapods but anterior limbs modified as wings
a. Feathers thought to evolved from reptilian scales
b. Light skeleton for flight
c. Endothermic, use metabolic E to maintain constant
temperature despite fluctuations in enviro temp
4. Mammalia
1. Key charact.
a. Mammary glands, produce milk, give birth to live young
b. Hair and fat layer under skin, help retain heat endothermic
c. High metabolic rate – supported by efficient respiratory and
circulatory systems
2. 3 groups: monotremes, marsupials, eutherians
3. Monotremes
a. Lay eggs, have hair, make milk, no nipples
b. Platypus n echidnas
4. Marsupials
a. Nipples, give birth to young, placenta, born early in dev and
complete embryonic dev while nursing in most spp helf within
marsupium (maternal pouch)
b. Kangaroos, koala
5. Eutherians
a. Known to have very complex placenta
b. Longer pregnancy than marsupials
c. Complete embryonic devlmpt in uterus