Ctenophora

Question 1

All animals share embryonic morphology and development as determined by

Answer 1

Hox gene

Question 2

Hox gene

Answer 2

master control genes

Question 3

Hos genes code

Answer 3

protein transcription factors
determine animal body plan

Question 4

These genes code protein transcription factors and ultimately determine animal body plan

Answer 4

Head/tail directionality, number of body segments, number/location of appendages, etc.

Question 5

Hox genes are are homologous in all animals

Answer 5

(except Ctenophora and Porifera)

Question 6

The order of hox genes determines

Answer 6

anterior/posterior axis, body segments, appendages

Question 7

Hox genes have undergone 2-4 duplication events

Answer 7

The additional genes allow for more and more complex body types

Question 8

Invertebrates

Answer 8

one set of Hox genes

Question 9

Vertebrates

Answer 9

4 sets of hox genes

Question 10

Ctenophora and Porifera do NOT have Hox genes

Answer 10

We will talk about how current research shows
Ctenophora are the most ancient of all animals

Question 11

All other animal clades have at least one set of Hox
genes

Answer 11

and up to four sets

Question 12

Some animals are diploblastic

Answer 12

they have 2 germ layers
asymmetrical and radial symmetrical animals

Question 13

Diploblastic Ectoderms

Answer 13

germ layer covers surface of animal

Question 14

diploblastic endoderm

Answer 14

germ layer forms wall of digestive tract

Question 15

Some animals are triploblastic

Answer 15

Three germ layers
Bilateral symmetrical animals

Question 16

Triploblastic Ectoderm

Answer 16

covers surface of animal

Question 17

Triploblastic Endoderm

Answer 17

forms digestive tract, respiratory tract, urinary tract

Question 18

triploblastic Mesoderm

Answer 18

forms muscle, bone, circulatory system, etc

Question 19

A coelom

Answer 19

is an internal body cavity derived from mesoderm
tissue
* Provides cushioning to internal organs
* Allows for body flexibility

Question 20

Triploblasts that do NOT have a coelom are called

Answer 20

acoelomates

Question 21

acoelomates

Answer 21

Their mesoderm region is completely filled with tissue
Example: Platyhelminthes (flatworms)

Question 22

Triploblasts that have a coelom that is completely surrounded
by mesoderm tissue are called

Answer 22

eucoelomates

Question 23

eucoelomates

Answer 23

Example: echinoderms (starfish) and chordates (animals with a
backbone)

Question 24

Triploblasts that have a coelom that is lined partly with
mesoderm and partly with endoderm are called

Answer 24

pseudo-coelomates

Question 25

pseudo-coelomates

Answer 25

Example: Nematoda (roundworms)

Question 26

Bilaterally symmetrical, eucoelomates can be further divided based on the

Answer 26

origin of their mouth/anus

Question 27

The archenteron

Answer 27

is the beginning of the gut

Question 28

the opening

Answer 28

is called the blastopore.

Question 29

The archenteron extends through the blastula

Answer 29

to create another opening. The opening on one end will become the mouth, the opening on the other end will become the anus.

Question 30

In Protostomes, the blastopore becomes the mouth

Answer 30

* This is more primitive * Arthropods, mollusks, annelids * Platyhelminthes is a protostome but only has one opening

Question 31

In Deuterostomes, the blastopore becomes the anus

Answer 31

* This is a novel, autapomorphic trait * Chordates and even echinoderms

Question 32

Phylum Ctenophora

Answer 32

Commonly called Comb Jellies * Not related to true jellyfish * Over 100 known species, all marine

Question 33

Ctenophora Phylogeny

Answer 33

* Thought to be related to Cnidarians * This put Porifera as the basal group of all animals *No Hox genes

Question 34

Just published research shows that Ctenophora

Answer 34

are actually the most ancient of all animals

Question 35

Compared genomes of ctenophores, sponges, and two-celled animals

Answer 35

sponges, the two-celled animals, and all other animal phyla exhibit a specific chromosomal fusion and rearrangement

Question 36

basal group

Answer 36

Ctenophores

Question 37

Ctenophora Superficially resemble medusa forms of Cnidaria

Answer 37

Morphologically, very different

Question 38

Morphology

Answer 38

* They have no stinging cells * They exhibit biradial symmetry * They are triploblastic protostomes * Mesoderm forms network of muscles * Their mesoderm is endodermal in origin (???) and it all becomes muscle

Question 39

Ctenophora Movement is produced by

Answer 39

cilia fused into their ctenes (comb plates) Most have 8 ctenes distributed around their body

Question 40

Ctenophora hunting

Answer 40

active hunters with adhesive cells on their retractable tentacles

Question 41

Their digestive “system” is unique

Answer 41

Prey enters mouth, travels to pharynx then gut where it is digested by enzymes * Solid food waste is then ejected back out of the mouth * What type of digestive system is this?

Question 42

They have anal pores...why?

Answer 42

Metabolic waste

Question 43

They have sophisticated

Answer 43

epithelial sensory cells with light receptors, mechanoreceptors, and gravi-receptors * Most are bioluminescent

Question 44

The nervous system is organized into

Answer 44

an epithelial nerve net and a mesogleal nerve net. There are two parallel nerves that extend into the tentacles.

Question 45

They are monoecious animals

Answer 45

Both male and female gonads

Question 46

They release both eggs and sperm into the water at the same time

Answer 46

* This is sometimes spontaneous and sometimes caused by the presence of other Ctenophores nearby * Can self-fertilize or reproduce with other Ctenophores