Phylum Annelida

Question 1

What is metamerism?

Answer 1

The repetition of identical anatomical units(segmentation), segments separated by sepa, allows different body regions to develop for different purposes or uses, independent movement by various segments.

Question 2

Locomotion in Annelids

Answer 2

The segmentation allows each part to move independently, aids hydrostatic skeleton and muscle contractions by allowing the animal to contract only a few segments at time in order to move.

Question 3

Predation in segmented animals

Answer 3

Segmentation allows specialisation of different body segments for different functions such as the head or the mouth.

Question 4

Nervous system in Annelids

Answer 4

The cerebral ganglion is in the head region, each segment is connected by ganglion branch from the ventral cord.

Question 5

Characteristics of leeches

Answer 5

Mostly freshwater/terrestrial, some marine, eyes(not image forming), no parapodia or chetae, 34 segments only, anterior and posterior sucker and not able to regenerate lost parts.

Question 6

Predation in leeches

Answer 6

Eyes detect changes in light, chemoreception, detect vibrations (using sensilla).

Question 7

Characteristics of blood sucking leeches

Answer 7

Have blade like jaws, secrete anticoagulants, use anesthetic so prey doesn’t feel bite, suck up fluids, drop off prey

Question 8

Locomotion in leeches

Answer 8

Body extended - attachment of anterior sucker to the substrate - longitudinal muscles contract bringing the posterior part of the body forward.
Swimming: dorsoventrally flatten their body and swim

Question 9

Reproduction in leeches

Answer 9

They Are hermaphrodites : bodies intertwine, sperm deposited into the clitellar area of each other, secretes cocoon and deposits eggs( cocoon contains nutrients) , cocoon dries to form a foam and young break out of cocoon.

Question 10

General features of oligochaetes (earthworm)

Answer 10

Mostly terrestrial, some freshwater, eat organic matter in the soil, ability to regenerate parts, head (simple), body segmented (up to 140) , segments marked by circular grooves calles annuli, has a circulatory system( 5 simple hearts).

Question 11

Earthworm feeding

Answer 11

First segment contains mouth , they consume the soil-extracting nutrients from decomposing organic matter, Are vital to soil health.

Question 12

Respiration and circulatory system in earthworms

Answer 12

Respiration: via diffusion, skin must be moist.

Circulatory : closed circulatory system blood enclosed with blood vessels, 5 simple hearts.

Question 13

Digestive system in earthworms

Answer 13

Mouth-muscular pharynx-passes through a narrow oesophagus-crop(storage organ)- gizzard (grinds food with the aid of stones) - food absorbed in the intestine- anus

Question 14

Hydrostatic skeleton in earthworms

Answer 14

Coelem is filled with fluid , contraction of longitudinal and circular muscles, alernate contractions allows movement .

Question 15

Reproduction in earthworms

Answer 15

Exactly the same as leeches

Question 16

General characteristics of polychaetes

Answer 16

Mostly marine, some freshwater , predators/filter feeders/ non-selective deposit feeders/selective deposit feeders/parasitic, respiration via diffusion or gills, body segmented ( parapodia present in segments), no suckers.

Question 17

What is parapodia ?

Answer 17

Chaetae in protection , gripping substrate, used for locomotion, respiration and reproduction, notopodium (respiration/locomotion), neuropodium (locomotion)

Question 18

Head in polychaetes

Answer 18

Greater cephalisation than other Annelids , mouth locales below the protomium and in front peristomium, eyes( in some) , jaws in some, head modified according to feeding types.

Question 19

Reproduction in polychaetes

Answer 19

Seasonal reproduction, sexes usually separate, fertilisation internal or external, larvae develop into trocophore larvae

Question 20

General features of Annelids

Answer 20

Terrestrial/marine/freshwater, free living/parasitic, coelomate, triploblastic, bilateral symmetry, segmented bodies, chetae in polychaetes and oligochaetes, non-chitinous cuticle, mostly hermaphrodites.