Topic 7, Rotifera

Question 1

What is the larger group that Rotifers are part of?

Answer 1

Gnathiferans

Question 2

What clades are the Rotifers part of?

Answer 2

Metazoa, Eumetazoa, Bilateria, Protostomia, Lophatrochozoa.

Question 3

What are the defining characteristics of Phylum Rotifera?

Answer 3

• Muscular pharynx with jaws for catching prey or attaching to substrate.
• Protostomes, triploblastic, bilateral, pseudocoelomate.
• Non-moulting

Question 4

Bazinga

Answer 4

Cheyziepop

Question 5

What are pharyngeal jaws?

Answer 5

They are calcified structures created by specialized epithelial cells.

Question 6

How do Rotifers grow?

Answer 6

• Mitosis ceases in early development
• They have a set number of cells that just get bigger when needed rather than an increase in cell number.

Question 7

Where do Rotifers Live?

Answer 7

95% freshwater
- 5000 individuals per L
5% marine

Question 8

Facts about Rotifers lifestyle

Answer 8

• Free living
• short generation time of 1-5 weeks
• Capture small algae and zooplankton

Question 9

What phylum is co-evolved with shrimp?

Answer 9

Rotifers

Question 10

Do Rotifers have parasitic forms?

Answer 10

Yes, there are a few species that are endoparasites.
They have modified body plans into a spiky-head worm

Question 11

Colonial form of Rotifers

Answer 11

• Can range from a few hundred to thousands
• attach to each other using flexible toes at posterior ends
• increase feeding and protection

Question 12

How do Rotifers excrete?

Answer 12

They have bilateral organization of excretion structures
- Lateral excretory canal runs posteriorly
- Waste exits at nephridiopore

Question 13

How do Rotifers attach to a substrate?

Answer 13

Glands secrete a sticky substance used for attachments.
- Motile species hold on with one or more toes
- Sessile species get fixed in place by secretions.

Question 14

Do Rotifers have eyes?

Answer 14

They have nerve clusters and a simple brain.
These are not true eyes, they either detect light or don’t.

Question 15

Rotifer’s Reproduction?

Answer 15

• Parthenogenesis is the most common way.
• Mothers can also import new DNA from fungi and plants
• When sexual reproduction does occur the male will make a hole in the body of the wall of female and inject sperm.

Question 16

What is cryptobiosis?

Answer 16

• It is when Rotifers dehydrate themselves and remain dormant.
• This helps increase survival in the spring when temporary pools dry up.
• Helps risk of infection.

Question 17

What are the Rotifers ecological role?

Answer 17

• Import food sources from consumers
• They are a transfer species ( transfer energy to higher tropic levels)
• Indicator species for water quality