Download Phylum Annelida

Phylum Annelida:
Segmented Worms
Phylum Annelida:
Segmented Worms
• Body divided into
repeating segments
2
1.
Annelida: annulus- ring, annual
2.
Body appears to be divided into
segments or metamerism- each segment contains body
systems, excretory, circulatory,
nervous, digestive
3.
Bilateral symmetry
4.
two body openings (mouth & anus)
5.
“ True” Eucoelomates-
6.
Live in every environment
7.
Reproduce sexually
(hermaphrodites)
8.
Setae- hair or bristles- except for
leeches
9.
Examples: bristleworms,
earthworms, leeches
Phylum
Annelida
Body Systems
• No Respiratory- gas
exchange through
skin
• *Circulatory
• Complete Digestion
• Nervous
• Muscular
• Excretory
• Reproductive
* Circulatory System
• Closed – blood always in
closed vessel
• Five pairs of aortic
arches(hearts)
• Ventral and dorsal blood
vessels and capillaries
• Hemoglobin
Digestive system
•
•
•
•
Crop-”stomach”- stores food
Gizzard- grinds food
Intestine- nutrient absorption
anus
Nervous System
• Pair of cephalic
ganglia(bundle of
nerves)
• Ventral nerve cord with
ganglia in each segment
(segmental ganglia)
Muscular System
• Longitudinal and
Circular muscles
• Allows for better
movement- can
thrash and inch,
raise head, etc.
Body wall
Epithelium
Circular muscle
Longitudinal muscle
9
Excretory System
• Wastes processed
through two
nephridia(kidney) in
each segment
• Nephridia, bladder
and excretory pore
Fig. 17.14
11
Reproductive System
-Hermaphrodites
• -sexual reproduction
• - trochophore larvae
Trochophore larvapaddlelike, bristles
Apical tuft
Stomach
Ciliary band
Mouth
Anus
13
Annelid development
14
Class Polychaeta
• Many setae(bristles)
• Parapodia(paddlelike
appendages
• Marine
• Gonads only appear during
breeding season
• Predators of small animals,
prey for larger
15
Class Polychaeta
Parapodium
Head
Tentacle
16
Polychaete Worm
Predatory
Jaw
Tentacle
Palp
Everted pharynx
Eye
Cirrus
Parapodium
17
Class Polychaeta
Fireworm
18
Sedentary Polychaete Lugworm
19
20
21
Class Oligochaeta
•
•
•
•
•
Few setae(bristles)
Clitellum
No parapodia
Hermaphroditic
Decomposers (aerate
soil)
• Food for larger animals
22
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
External Structures of an Earthworm
23
Lumbricus terrestris
• Feed on decaying
organic matter
• Enrich soil
24
25
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Internal Structures of an Earthworm
26
27
Digestive structures:
o Crop: temporary storage sac
after mouth
o Gizzard: sac with muscular
walls to grind soil
o Intestine: stretches length of
body to aid in digestion of soil
o Anus: wastes are removed
Earthworms
Anus
Setae
gizzard
Clittelum
Other structures:
• Setae: bristles used for
movement (ventral side)
• Clittelum: enlarged segment;
secretes mucus & contains
reproductive parts
crop
Mouth
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Earthworm Reproduction-sexual
29
Class Hirudinea
• Anterior & posterior
sucker-ectoparasite
• No setae
• hermaphrodites
• Most live in fresh water
• Dorsoventrally
compressed(flat)
• Ex. leeches
• Feed
– Invertebrates
– Body fluids
– Blood
31
32
Leeches
o
o
o
o
o
o
Parasitic segmented worm
Most live in fresh water
Have no bristles for
movement
move with muscular
contractions
Suckers used for attachment
to host
Some have suckers on tail
also
o Secrete anesthetic during bite
and release anticoagulant into
blood during feeding (to keep
blood flowing)
o Leeches were used in medical
procedures years ago to “bleed”
the sick
o remove “bad blood”
o now they are used in cosmetic
surgery, digit and limb
reattachment, and blood removal
of bruises