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Phylum Annelida
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Phylum Annelida From the Latin Annellus a “______________”.
______________ body ______________ – segment in the body ________ Small ____________ structures ___________ in leeches ___________ divided by septa ______________ tissue 3
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Phylum Annelida The segments of an annelids body are separated by __________________ called septa. Most of these segments are the ________ but a few are modified to perform special _______________ such a photoreceptors, antennae, etc. 4
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Metamerism Septa Pygidium Prostomium Peristomium
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Phylum Annelida Annelids range in size from the ______________________, of which Michrochaetus rappi (Michrochaetus michrochaetus) is the largest average length of _____ m (54 ins) and a record breaking specimen has been recorded that measured ____ metres (22 ft) in length, it was 2cm (0.8 ins) in diametre. The smallest Annelid known to science is Chaetogaster annandalai full grown at ___ mm (0.02 ins).
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General Annelid Anatomy
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Body Plan ________________ ________________ symmetry _______ coelom
Annelids are the first major phyla showing _______________ (metamerism) which is advantageous to _______________, safety, and tagmatization
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Feeding Annelids have a ___________ digestive system
The digestive tract is a long tube from the _______ to the _______. Their system contains mouth, ___________, esophagus, ________, ___________, intestine and anus They have a pharynx which is used to ________ up the larger particles of food. 9
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Feeding Some annelids are ______________.
Carnivorous annelids can _________ the pharynx through the mouth. These have two or more sharp ______ attached to it which are used to catch its prey. In earthworms the pharynx acts like a _______ pulling in soil and detritus through the mouth and ___________ it into the gut. In ___________ annelids the pharynx is used to suck _______ from the host. Some aquatic annelids are _______ feeders and use __________ structures to catch food particles.
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Respiration Aquatic annelids breathe through ______.
Many annelids take in ___________ and give off carbon dioxide through their ______. The skin must stay _________ for this type of gas exchange to occur. ______________ annelids secrete a thin protective coat called a __________ to hold moisture around them. 11
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Circulatory System Annelids usually have a ___________ circulatory system with ______ blood vessels running the length of the body. In earthworms there are several ______ vessels connected to these blood vessels in the _____________ part of the worm. The ring vessels are _____________ and contract in rhythm so they are sometimes referred to as _________. They do help _________ blood through the system. In other annelids the blood is moved around by the worms _____________. 12
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Closed Circulatory System
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Excretion Solid waste is removed through the anus while waste resulting from ___________ activity is removed by a pair of ___________ in each segment of the body. 14
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Nervous System Annelids have a well developed nervous system.
________ organs are most developed in the _____________ marine annelids. They often have sensory ___________, photoreceptors, two or more eyes, and ___________. 15
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Nervous System cont’d A statocyst is an organ used to detect _________ while they are in the water. Many other annelids have simpler sensory systems like the earthworm. They rely only on _______ in their skin to sense their environment. 16
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Nervous System Fig 17 17
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Movement Annelids have ______ major groups of muscles they use to move. ___________________ muscles run from the front to the rear. These make the worm __________ when they are contracted. The other group runs in __________ around the worm. When they are contracted they make the worm __________. These two muscle groups are used together to help the worm __________ forward. 18
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Movement
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Setae – help in movement
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Reproduction Most annelids reproduce _____________ but a few can reproduce by ___________. Oligochaetes are ______________________ and during copulation they line up facing in the ___________ direction The ___________ secretes a mucous that holds the worms in place Later, the clitellum acts as a ___________ where the fertilized _____ develops 21
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Earthworm Reproduction
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Trochophore larva Apical tuft Stomach Ciliary band Mouth Anus
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Annelid development
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Classification Class Polychaeta (many hairs)
Class Oligochaeta (few hairs) Class Hirudinae (leeches)
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Class Polychaeta Many _______ Parapodia = “____________”
Characterized by paired _______________ appendages on the segments. The appendages are tipped with ___________ that help the move about. They live in the _________, usually around reefs. 26
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Fig. 17.3 27 27
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Class Polychaeta Parapodium Head Tentacle 28
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Polychaete Worm _____________ Jaw Tentacle Everted pharynx Palp Eye
Cirrus Parapodium 29 29
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Nereis 30
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Class Polychaeta Fireworm
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Sedentary Polychaete Lugworm
Fig. 17.5 32 32
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Fig. 17.4 33 33
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Pelagic* Polychaete *Drift in the open ocean 35
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Class Oligochaeta Few _________
have bristles but they are much ___________ and help the earthworm ___________ through the soil. ___________ _____ parapodia ________________ Both male and female parts 39
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Earthworms play an important role in soil fertility
Return ___________ to soil by decomposing dead leaves and organic matter Burrowing allows ____ and water to penetrate to roots Tunnels __________ soil so roots can grow more easily “intestines of the earth” -Aristotle 40
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Lumbricus terrestris - earthworm
__________ soil Exceedingly important in soil ____________, particularly in temperate areas. Without them, ________________ and perhaps the whole of human society as we know it would never have evolved. 41
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External Structures of an Earthworm
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. External Structures of an Earthworm
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The Anatomy of an Earthworm
Section 27-3 Anus Clitellum Circular muscle Longitudinal muscle Nephridia Ganglia Ring vessels Reproductive organs Ventral blood vessel Ganglion Brain Mouth Dorsal blood vessel Crop Gizzard Body segments Setae
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Fig c
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Body wall Epithelium Circular muscle Longitudinal muscle
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Class Hirudinea - Leeches
No ______ Anterior & posterior _________ Most live in ________ water Feed Invertebrates Body fluids ________
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Class Hirudinea Usually no more than __ cm in length but some tropical species can reach ____ cm. After they attach to a host they release a substance called ___________ into the wound. This keeps the blood from ___________. A leech can take in up to ____ times its weight in blood during a single feeding. 47
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Fig
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PARASITIC SEGMENTED WORMS LEECHES
Medical uses
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