nemertea

Question 1

Nemerteans
Introduction
4 points

Answer 1

1. Ribbon worms; unsegmented and extensible bodies
2. Global distribution
3. Predominately benthic, some commensal [organism living off another one but host not affected]
4. Marine, freshwater and terrestrial

Question 2

Nemerteans

Classification

Answer 2

Kingdom: Metazoa
Phylum: Nemertea
Class: Anopla, Enopla

Question 3

Nemerteans
Key characteristics
5 points

Answer 3

1. Bilaterally symmetrical
2. Triploblastic
3. Tissues, organs, complete nervous system, and closed circulatory system surrounding a through-gut
4. Dioecious [males and females]
5. Unique proboscis
6. Rhynchocoel (different to annelids)

Question 4

Nemerteans
Body structure
3 points

Answer 4

1. Triploblastic
   Ectoderm,
   (cellular) mesoderm,
   endoderm
2. Body comprised of
   ciliated [locomotion] epidermis, muscular dermis,
   cellular mesenchyme,
3. Acoelomate [don’t have body cavity]

Question 5

Body plans recap

Porifera

Answer 5

Diploblastic, Acoelomate

1. gut
2. endoderm
3. ectoderm

Question 6

Body plans recap

Nemertea

Answer 6

Triploblastic Acoelomate

1. gut
2. endoderm
3. mesoderm
4. ectoderm

Question 7

Body plans recap

Vertebrates

Answer 7

Triploblastic, coelomate

1. gut
2. endoderm
3. coelom
4. mesoderm (split by coelom)
5. ectoderm

Question 8

Nemerteans
Locomotion
3 points

Answer 8

1. Muscular crawling and ciliated ‘gliding’
2. Burrowing
3. Anguilliform swimming [quick anti-predatory response]

Question 9

Nemerteans
Feeding - Predators
3 points

Answer 9

1. Huge variability in prey
2. Some species have toxic stylets [ can only use once but replaced]
3. Some worms hunt using the mucus trials left by gastropods or other worms

Question 10

Nemerteans

Rhynchocoel

Answer 10

captures prey with venom

allows for specialisation

Question 11

Nemerteans
Feeding
4 points

Answer 11

1. Scavengers
2. Grazers? [some evidence]
3. Commensal relationships [with bivalve?]
4. Ectoparasites

Often found inside
crustaceans

Feed on egg masses

Question 12

Nemerteans
Sexual Reproduction
4 points

Answer 12

1. Dioecious
2. External fertilisation

Indirect development [eggs sperm mix in water, series of larval stages]

Mixed development

3. Internal fertilisation

Mixed development

Egg capsules

4. Hermaphrodites

Protandric [start as male,

become female]
Simultaneous

Question 13

Nemerteans
various degrees of Regeneration (asexual reproduction)
3 points

Answer 13

1. Transverse fission
2. Fragmentation
3. Best example is the genus Lineus

Question 14

Nemerteans; Class Anopla

2 points

Answer 14

1. ‘Unarmed’ nemerteans
   Mouth separate from proboscis [no stylet on end]
2. Longitudinal nerve cord in Epidermis, dermis or muscle layers

Question 15

Nemerteans; Class Enopla

4 points

Answer 15

1. Armed nemerteans
2. Mouth united with proboscis
   (rhynchocoel still present)
3. Longitudinal nerve cord
   Mesenchyme
4. Can be terrestrial, freshwater, parasitic