Platyhelminthes

Question 1

8 traits of Phylum Playhelminthes

Answer 1

1. Triploblastic - has ectoderm, mesoderm, and endoderm
2. Acoelomate
3. Incomplete gut - one opening to GVC. Anus lost
4. Dorsoventrally flattened
5. Cephalization - brain
6. Ladder-like nervous system
7. Excretory system - has a protonephridia, which is an excretory tube that lacks an internal opening
8. Complex reproductive and musculature systems

Question 2

Synapomorphy of Platy (1)

Answer 2

Incomplete gut. It lost the anus and only has one opening to the GVC

Question 3

3 major subgroups of Platy

Answer 3

1. Rhabocoels
2. Polycladida
3. Tricladia

All of which are free-living

Question 4

Inverted pigment cup ocellus

Answer 4

Detects light/dark

Question 5

Auricle

Answer 5

A chemoreceptor for taste and smell

Question 6

Dorsoventral muscle

Answer 6

Makes it short and wide

Question 7

Lateral muscle

Answer 7

Makes it tall and narrow

Question 8

Circular muscle

Answer 8

Makes it longer

Question 9

Longitudinal muscle

Answer 9

Shorter and taller

Question 10

Antagonistic muscles

Answer 10

Muscles that opposes the action of another

Ex. Dorsoventral and lateral muscle

Question 11

Digestion of Platy

Answer 11

They will extracellularly intake food. The nutrients from the food will be absorbed and phagocytosis will occur. The final process occurs intracellularly

Question 12

Does Platy have a mesoglea or mesenchyme?

Answer 12

Mesenchyme

Question 13

Reflective pigment

Answer 13

Allows them to know the direction of light because light can only be sensed in one direction. It wants to move away from light

Question 14

Types of asexual reproduction (2)

Answer 14

1. Transverse fission
2. Regeneration - tail cells only build tail cells and same concept for head. Middle cells can build either

Question 15

Types of sexual reproduction

Answer 15

1. Hermaphroditic - complete set of male and female parts. This means that Platy are monoecious
2. Mutual cross fertilization
3. Internal fertilization via hypodermic impregnation - stabbing mate with sperm. Can lead to penis fencing

Question 16

Apical sense organ

Answer 16

The larval brain that consists of flagella

Question 17

Muller’s larva

Answer 17

Covered in cilia, allowing them to move around

Question 18

Stereogastula

Answer 18

The stage where epiboly occurs. When compared to invagination in Cnidaria, it is how Platy undergoes gastrulation

Question 19

Blastopore

Answer 19

First gut formation

Question 20

4d

Answer 20

Develops into the mesentoblast, which gives rise to all mesoderm and endoderm