Lophotrochozoa

Question 1

Which clades are combined to form the lophotrochozoans?

Answer 1

Lophophorata and trochozoa.

Question 2

Describe the phylum annelida.

Answer 2

Triploblastic as an embryo.
Mesoderm goes on to form the coelom in adults.
Long, segmented body covered by a cuticle.
0.5mm to 4m long.
Closed circulatory system.

Question 3

Define schizocoely.

Answer 3

When secondary body cavities are formed by splitting a solid mass of mesodermal embryonic tissue.

Question 4

Describe the segmentation of annelids.

Answer 4

Clearly segmented but homonomous.

Question 5

What are the segments known as in annelids?

Answer 5

The segments are known as metameres and are separated by septa.

Question 6

What organ systems are found in annelids?

Answer 6

Digestive system.
Circulatory system.
Cephalised nervous system.
Excretory system.

Question 7

Describe the class polychaeta.

Answer 7

A class of annelids.
Possess oblique muscles running at an angle to longitudinal muscles.
Each segment has parapodia covered in chaetae.

Question 8

What gives polychaetes their name?

Answer 8

Each segment has a pair of parapodia that bear bristles (chaetae made of chitin) for movement.

Question 9

Describe the anatomy of earthworms as a group.

Answer 9

Very similar to polychaetes except for parapodia.

Possess a metanephridium made up of nephrostomes.

Question 10

What is a metanephridium?

Answer 10

An excretory gland.

Question 11

Describe the anatomy of leeches as a group.

Answer 11

No septa (no separate cavities).
Don't pass food through the gut - blood feeders.
Suckers at both ends.
Oblique muscles running at an angle.
Reduced coelom.

Question 12

Describe locomotion in segmented lophotrochozoa.

Answer 12

1. Longitudinal muscles contract.
2. Body expands.
3. Circular muscles contract.
4. Body elongates.

Question 13

Describe locomotion in the errantia subclass of polychaetes.

Answer 13

Parapodia movement also contributes to locomotion. Undulation is used to swim.

Question 14

Describe locomotion in leeches.

Answer 14

Leeches stretch out, then detach and repeat using their sucker pads.

Question 15

What are the different feeding strategies for small and large food particles?

Answer 15

Small particles are consumed via suspension feeding. An eversible pharynx is used for large food particles.

Question 16

What are the 3 main groups of earthworms?

Answer 16

Endogeic, epigeic and anecic.

Question 17

Describe endogeic earthworms.

Answer 17

Rich soil feeders, small in size and produce horizontal burrows.

Question 18

Describe epigeic earthworms.

Answer 18

Litter feeders, small in size. Non-burrowing.

Question 19

Describe anecic earthworms.

Answer 19

Litter + soil feeders, large in size and produce extensive vertical burrows.

Question 20

Describe reproduction in polychaetes.

Answer 20

Gonochronistic but with no permanent sex organs.
Gametes develop in coelom.
Many reproductive strategies, both sexual and asexual.

Question 21

Define stolonisation.

Answer 21

Each of the small sections of the organism eventually break off to become a separate individual.

Question 22

Define epitoky.

Answer 22

Entirety/Part of the animal metamorphoses into a sexually mature form.

Question 23

Describe reproduction in earthworms.

Answer 23

Mainly hermaphrodites.
Cross-fertilisation is most common form.
External fertilisation.
No larval stage.

Question 24

Describe reproduction in leeches.

Answer 24

No asexual reproduction.
Similar to earthworms (oligochaetes).
Clitellate and hermaphrodite.
Internal mating using a spermatophore is the commonest form of mating.