Exam 3

Question 1

Protostomes

Answer 1

Extremely diverse, monophyletic group in the animal phyla

Includes insects, earthworms, bees, common seafoods, etc.

Question 2

Embryonic development of protostomes

Answer 2

Protostome = “mouth first”

Spiral cleavage

Mouth develops before anus

Question 3

Two major protostome subgroups

Answer 3

Lophotrochozoa and ecdysozoa

Question 4

Lophotrochozoa

Answer 4

Includes mollusca, rotifera, annelida, and platyhelminthes

Monophyletic group defined by lophophore, trochophore, spiral cleavage, and tube-like bodies

Question 5

Lophophore

Answer 5

Specialized feeding structure that rings the mouth and functions by suspension feeding

Question 6

Trochophore

Answer 6

Type of larva (present in some phyla) that has a ring of cilia around the middle that functions for sweeping and sometimes feeding

Question 7

Development of tube-like body

Answer 7

Ectoderm becomes the outer tube (skin), endoderm becomes the inner tube (gut), and the mesoderm becomes muscles and organs between outer and inner tubes

Question 8

Flatworms

Answer 8

Lophotrochozoa

Has a broad, flat body and lacks a coelom and other structures necessary for gas exchange and circulation

Includes planarians, which regenerate if cut in half

Question 9

Annelids

Answer 9

Lophotrochozoa

Segmented worms

Include polychaeta, oligochaeta (earthworms), and hirudinea (leeches)

Question 10

Mollusks

Answer 10

Lophotrochozoa

Highly diverse and monophyletic

Have a characteristic body defined by a foot, a visceral mass, a mantle, and usually a radula

Includes chitons, bivalves, gastropods, and cephalopods

Question 11

Chitons

Answer 11

Dorsal shell made of plates

Foot is large and muscular; works as hydrostatic skeleton called muscular hydrostat

Question 12

Bivalves

Answer 12

Clams and mussels

Foot is modified as a digging appendage

In clams, mantle has two siphons extending into a water column, controlling incurrent and excurrent water flow over the gills

Question 13

Cephalopods

Answer 13

Squid and octopus

Foot is modified to form tentacles

Mantle cavity fills with water, muscle contracts, and stream of water is forced out to create a jet propulsion

Question 14

Gastropods

Answer 14

Slugs and snails

For snails, foot works as a muscular hydrostat

Question 15

Visceral mass

Answer 15

Region containing most of the main internal organs and the external grill

Separates the internal organs from the hydrostatic skeleton

Has a key adaptation separating it from the foot

Question 16

Mantle

Answer 16

Outgrowth of body wall that covers visceral mass, forming enclosure cavity

Secretes a shell made of calcium carbonate

Many diverse adaptations and functions

Question 17

Ecdysozoa

Answer 17

Includes arthropods

Defined by intermittent growth via molting

Question 18

Molting

Answer 18

Shedding of soft cuticle or hard exoskeleton followed by fluid causing the body to expand and a larger cuticle/exoskeleton forms

Species undergo a succession of molts over time, sometimes with dramatic morphological changes

Question 19

Arthropods

Answer 19

Defined by key body features: segmentation, exoskeleton, and jointed appendages

Includes myriapods, insects, crustaceans, and chelicerates

Question 20

Segmentation

Answer 20

Segmented body is organized into prominant regions called tagmata

Insects are divided into head, thorax, and abdomen

Spiders and crayfish are divided into cephalothorax and abdomen

Question 21

Convergent evolution of segmentation

Answer 21

Annelids also have body segmentation, although they are in a different lineage from arthropods

Question 22

Exoskeleton

Answer 22

Made primarily of chitin, strengthened by calcium carbonate in crustaceans

Question 23

Jointed appendages

Answer 23

Enable the rigid body to move

Question 24

Myriapods

Answer 24

Arthropods

Millipedes and centipedes

Have long, segmented trunks

Question 25

Insects

Answer 25

Arthropods

Three tagmata, unbranched appendages, and one pair of antennae

Question 26

Crustaceans

Answer 26

Arthropods

Two to three tagmata, branched appendages, and two pairs of antennae

Question 27

Chelicerates

Answer 27

Arthropods

Spiders and scorpions

Two tagmata

Question 28

Deuterostomes

Answer 28

Large and complex animals, mostly vertebrates

Meaning “second mouth” because the anus develops before the mouth in embryonic stages

Includes echinoderms and chordates

Question 29

Echinoderms

Answer 29

Includes sea stars, sea urchins, and other marine animals

Monophyletic, contains three main synapomorphies: radial symmetry, endoskeleton, and water vascular system

Question 30

Endoskeleton

Answer 30

Hard protective and supportive structure

Formed by secretion of calcium carbonate inside the skin; in some species plates fuse together and in others plates stay flexible

Question 31

Water vascular system

Answer 31

Series of branching, fluid-filled tubes and chambers that form a hydrostatic skeleton

Controls tube feet: elongated, fluid-filled appendages with an ampulla inside the body and tube-like podium projecting on outside

Question 32

Radial symmetry

Answer 32

Most species are bilaterally symmetrical as larvae and later develop pentaradial symmetry (see diagram)

Question 33

Chordates

Answer 33

Include vertebrates, urochordates, and cephalochordates

Synapomorphies include pharyngeal gill slits, dorsal hollow nerve cord, notochord, and muscular post-anal tail

Question 34

Cephalochordates

Answer 34

Include lancets and amphioxus

Small, mobile suspension feeders that resemble fish, burrow in sand, and have no eyes or jaw

Have a dorsal hollow nerve cord that runs parallel to notochord

Notochord stiffens body and results in muscular contractions and movement

Question 35

Urochordates

Answer 35

Includes tunicates

Both larvae and adults have pharyngeal gill slits for feeding and gas exchange

Notochord, dorsal hollow nerve cord, and tail only occur in larvae or sexually mature forms of motile species

Question 36

Vertebrates

Answer 36

Includes hagfish, lampreys, sharks, rays, bony fish, amphibians, mammals, reptiles, and birds

Dorsal hollow nerve cord becomes the spinal cord

Pharyngeal pouches and notochord present in embryos but not once born

Synapomorphies: vertebrae and cranium

Question 37

Vertebrae