ORIGIN OF CHORDATES

Question 1

A large phylum of animals that includes the
vertebrates together with the sea squirts and
lancelets.

Answer 1

Chordates

Question 2

Chordate is A phylum of animals having at least at some stage of
development (3)

Answer 2

Notochord
Dorsally situated CNS
Gill slits

Question 3

The chordate evolved during what period

Answer 3

Cambrian

Question 4

Chordate Evolved during the Cambrian period from a __ ancestors (__,__)

Answer 4

Deuterostome
Echinoderm
Hemichordates

Question 5

Chordate origin was proposed by a French zoologist __

Answer 5

Geoffrey Saint Hilaire

Question 6

Chordate body plan was
derived from a turned-over
version of

Answer 6

Annelid

Question 7

He enumerated several
criticisms/differences that
surpass similarities (chordate origin)

Answer 7

Georges Cuvier

Question 8

Segmentation of annelid is _ to _

Answer 8

Skin
Gut

Question 9

Type of cleavage in annelids

Answer 9

Spiral cleavage

Question 10

Type of cleavage in vertebrates

Answer 10

Radial cleavage

Question 11

Annleids are protostome/deuterostome

Answer 11

Protostomes

Question 12

Vertebrates are protostomes/deuterostomes

Answer 12

Deuterostomes

Question 13

Known as the first mouth in chordate phylogeny

Answer 13

Protostomes

Question 14

Known as the second mouth in chordate phylogeny

Answer 14

Deuterostomes

Question 15

Proposed that echinoderm
larvae gave rise to chordates
by neoteny

Answer 15

Johannes Muller (1860)

Question 16

Refers to the retention of
juvenile features in the adult
animal

Answer 16

Neoteny

Question 17

__ are also
deuterostomes and possess
mesodermal skeletal elements
(made from CaCO3
).

Answer 17

Echinoderms

Question 18

__ is a small fossil group of echinoderms with
skeleton similar to that echinoderm with a tail similar to the
stalk of crinoid proposed to be a link between echinoderms
and vertebrates

Answer 18

Calcichordate

Question 19

Hemichordate origin
suggested that ancestral
deuterostomes were
sedentary tentacle feeders
whose mucous-laden
ciliated tentacles served to
trap planktons as they were
waved in water (like modern
hemichordates).

Answer 19

Romer (1959)

Question 20

Calcichordate fossil

Answer 20

Echinoderm origin

Question 21

Hemichordate fossil
Acorn worm
Balanoglossus

Answer 21

Hemichordate origin

Question 22

Urochordate origin
__ and __ tadpole-like
larva of urochordates which
carries typical chordate
characters.

Answer 22

W. Garstang (1928)
Berrill (1955)

Question 23

suggested
that chordates evolved from
some sessile filter-feeding
urochordate by the larval
stage evolving into adult by
neoteny and by losing the
sedentary adult stage

Answer 23

W. Garstang (1928)

Question 24

Tunicate adult
Tunicate larva

Answer 24

Urochordate origin

Question 25

primitive and advanced
characters of
cephalochordates possess
all chordate characters in
typical state
(Theory and person)

Answer 25

Cephalochordate origin
Chamberlain (1900)

Question 26

Pikaia gracilens fossil
Modern amphioxus

Answer 26

Cephalochordate origin

Question 27

proposed that the common
ancestor of echinoderms and
chordates was a sessile ciliary
arm feeder that lived in the
plankton-rich environment of
the Cambrian.
* Later evolved in a free
swimming form at a time of
food scarcity.
(Theory and author)

Answer 27

Combined theory
E.J.W Barrington (1965)

Question 28

Yuknessia
Pikaia gracilens

Answer 28

Combined theory

Question 29

(4) structures of a chordate

Answer 29

Dorsal hallow nerve cord
❑Notochord
❑Pharyngeal pouches/slits
❑Postanal Tail

Question 30

Dorsally located.
* Nerves are branched to this
cord at regular intervals and
connect to internal organs,
muscles, and sense organ.

Answer 30

Hollow nerve cord

Question 31

A long supporting rod that
runs through the body just
below the nerve cord.
* Most chordates have this during their embryonic stage.

Answer 31

Notochord

Question 32

These are paired structures in the
throat (pharynx) region.
* In some animals such as fishes
and amphibians these slits will
develop into gills, in higher
chordates it will disappear during
development.

Answer 32

Pharyngeal slits

Question 33

Pharyngeal slits
adults that live in water and breathe via gills

Answer 33

Permanent slits

Question 34

Pharyngeal slits
Adults live on land

Answer 34

temporary slits

Question 35

Posteriorly located.
* contains bones and
muscles used by animals
for swimming and
balancing their body.

Answer 35

Tail

Question 36

2 groups under phylum chordata

Answer 36

Group Protochordata (Acrania)
Group Craniata

Question 37

Subphylum
Sea squirts and tunicates
Notochord, nerve cord, post-anal tail
present only in free-swimming larvae;
Ascidian adults sessile’ or occasionally
planktonic, encased in tunic that contain
some cellulose; marine

Answer 37

Subphylum Urochordata

Question 38

Subphylum
Lancelets(Amphioxus) , Assymetron
Notochord, nerve cord, post-anal tail
and gill slits persist throughout life;
body laterally compresses and
transparent; fishlike form

Answer 38

Subphylum Cephalochordata

Question 39

Gr. A- without, and gnathos – jaw
Cyclostoma: hagfishes and lampreys
Without true jaw and appendages

Answer 39

Superclass Agnatha

Question 40

Fish-like; jawless; no paired
appendages; suctorial mouth with
horny teeth and rasping tongue;
nasal sac not connected to
mouth; seven pairs of gill slits

Answer 40

Class Cephalaspidomorphi

Question 41

Fish-like; jawless; no paired
appendages terminal mouth with four
pairs of tentacles; no sac with duct to
pharynx; 5 to 15 pairs of slits; partially
hermaphroditic. Hagfishes

Answer 41

Class Myxini

Question 42

Gr. Gnathos – jaw and stoma – mouth
Jawed fishes and all tetrapods
With jaws and usually paired appendages

Answer 42

Superclass Gnathostomata

Question 43

Gr. Chondros - cartilage and ichthys
– fish
Streamed liked fish body with
heterocercal tail; cartilaginous
skeleton; five to seven gills with
separate openings; no operculum;
no swim bladder

Answer 43

Class Chondrichthyes

Question 44

Gr. Osteon – bone and ichthys – fish
fusiform body; mostly ossified skeleton
single gill opening on each side covered with
operculum,; usually with swim bladder

Answer 44

Class Osteichthyes