Echinodermata, Chordata

Question 1

Evolution of bilateral symmetry (2-sided symmetry)

Answer 1

Is Derived character (not found in metazoa)

Animals w/ this have a dorsal (top) side and a ventral (bottom) side as well as a right and left side

Question 2

Anterior vs posterior

Answer 2

Front and back

Question 3

Cephalization: with radial and bilateral symmetry

Answer 3

W/ radial symmetry: networks of individual neurons.

Radial animals are often sessile (fixed in one place) or weakly swim (drifting)

W/ bilateral: clustering of neurons like gangila/brains and clustering of sensory organs which leads to active movement

Question 4

Evolution of complete gut derived vs ancestral character

Answer 4

Ancestral characteristic- gastravascular, and cavity in cnidaria

Derived characteristics is complete gut

Question 5

2 fates of complete gut

Answer 5

1. Becomes mouth
   Clade= protostomia (prot is first, stome is mouth)
   A might form later
2. Formation of a
   Clade= deuterostomia- mouth forms later
   Ex: chordates

Question 6

Phylum echinoderm
clade: starfish

Answer 6

Meaning: spiny skin
Hydraulic canals (use water to move), tube feet, locomotion
ampulla: constantly fill and eject water
most adult echinoderm have radial symmetry (pentaradial) but echinoderm larvae have bilateral symmetry
had complete gut (mouth and A)
endoskeleton

Question 7

phylum chordata

Answer 7

chordates and vertebrates
are bilateral animals that belong to a clade of animals called deuterostome

Question 8

segmentation

Answer 8

hox genes help w/ this
consists of repeating body units

Question 9

characteristics of chordates

Answer 9

1. notochord: like a rod- provides strength and support, usually made of cartilage
2. dorsal hollow nerve chord- developed in the central nervous system spinal chord same tissue that makes skin aka ectoderm)
3. gill/slits- does not function entirely as gills, originally for suspension feeding/moving water and filtering food out and putting into the digestive track
4. post-anal tail
   can be reduced during embryonic development, consists of skeletal elements and muscles

Question 10

chordate clade: cephalochordata

Answer 10

most basel froup of living chordates= lancelets
maintains chordate characteristics across lifespan
have muscular somites

Question 11

chordate clade: urochordata

Answer 11

ex: tunicates
chordate characteristic only in larvae stage- also
known as undergoing metamorphosis (characteristics disappearing)

captures food particles with cilia and water exits through excurrent siphon

Question 12

chordate clade: vertebrates

Answer 12

animals with vertebrae (and skulls)
skeletal and nervous systems allow vertebrates to be more efficient at capturing food and invading characters

Question 13

vertebrates derived traits (unique to this clade)

Answer 13

• vertebrae enclosing a spinal cord
  -elaborate skull
  -fin rays (in aquatic forms)
  -2 or more set of hox genes
  -embryo folds in itself and makes neural crest

Question 14

evolution of vertebrae: its basel and examples

Answer 14

basel= jawless fish
ex hangfish
-scavengers, skull made of cartilage, retains notochord as adults, produces slime

ex: lampreys
-most are parasites, skeleton made of cartilage, clamp round jawless mouth

Question 15

evolution of jaws (gnathostomes) and clade

Answer 15

seemed to evolve from skeletal supports of gill slits- making bigger brain (sensory), and lateral line

clade: sharks (Chondrichthyans), mammels, reptiles, bird

Question 16

evolution of lungs and bones (clade)

Answer 16

osteichthyan clade- means bony skeleton
ex: ray finned fish like salmon, trout

Question 17

evolution of limbs

Answer 17

fins replaced with limbs, head separated from body (neck), bones of pelvis are fused to backbone

adult= loss gills
ex: amphibians (both water and land) frogs larvae stage is aquatic with gills

Question 18

what do tetrapods have

Answer 18

they are gnathostomes (jaw) that have limbs
adult tetrapods dont have gills

Question 19

evolution of amnion (laying eggs)

Answer 19

clade= amniota (birds, reptiles, some mammels)
derived character= amniotic egg w/ 4 layer membrane

can now lay egg in land and dont need to be on water/moist

-improved jaw strength
-ectotherms (dont regulate body heat) but research found some birds can be endotherm

Question 20

4 layer membrane of amnion

Answer 20

1. amnion- shock absorber
2. chorion- gas exchange
3. yolk sac- provide nutrients
4. allantois- waste storage

Question 21

evolution of milk and hair and 3 clades

Answer 21

Mammalia
mammal mothers nourish young with milk
have hair for heat and efficient kidneys to remove waste and to conserve water

1. monotremata- lays egg and milk patch
   ex: platupus
2. marsopials- babies are undeveloped (kangaroo), short gestation
3. long gestration (human, elephant), better development