9 Metamerism & Repd
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“Metamerism & Reproduction in Annelida” A presentation compiled from various sources by
Dr. PARVISH PANDYA, Zoology Dept. Bhavan’s College, Andheri. Dr. PARVISH PANDYA’s presentation
Sites from which presentations have been downloaded and later editted. I am indeed thankful to them for their kindness and support : http://esg-www.mit.edu:8001/esgbio/cb/org/organelles.html http://faculty.pnc.edu/jcamp/parasit/parasit.html http://www.amnh.org/rose/hope/creatinghope/ http://www.biology.eku.edu/SCHUSTER/bio%20141/POWERPOINT %20NOTES/Intro%20to%20Protozoa_files/fullscreen.htm http://www.biosci.ohio-state.edu/~zoology/eeob405/ http://www.tulane.edu/~wiser/protozoology/pwpt/ http://www.iep.water.ca.gov/suisun/photos/wildlife.html http://www.uta.edu/biology/marshall/2343/ http://www.uta.edu/biology/faculty/faculty.html http://www.okc.cc.ok.us/biologylabs/Documents/Zoology/PowerPoint.htm http://bio.fsu.edu/ http://www.aw-bc.com/ http://www.nhm.org/ http://www.geo.cornell.edu/eas/education/course/descr/EAS302/presentations/ It is very easy to find mistakes in these presentations…..I request you to kindly rectify them and supply me the modifications needed at [email protected] Thanks a lot and have fun in teaching & learning Zoology…. Dr. PARVISH PANDYA’s presentation
Phylum Annelida
PHYLUM ANNELIDA (Annulus: Little rings) • HABIT: Free living or Ectoparasitic. • HABITAT:Sea water, fresh water, moist soil. • SIZE : It varies from 1 mm to 3 metres. • SHAPE : Body is long, cylindrical or flattened.
Dr. PARVISH PANDYA’s presentation
What is a segmented worm? •Long and narrow •Closely related to crabs and snails •Has a body built of ring-like segments
Dr. PARVISH PANDYA’s presentation
METAMERISM Metamerism is the phenomenon in which the
body of an animal is divided into anteroposterior row of similar part or sections. These sections are called as segments or metamers or somites. It involves a longitudinal division of body of a bilaterally symmetrical organism into a linear series of similar segments.
Dr. PARVISH PANDYA’s presentation
Metamerism •Have an anterior prostomium and posterior pygidium; both nonsegmented • Body is divided into a linear series of similar parts or segments, and each segment is called a metamere • The pattern of repeated segmentation is called metamerism • Each metamere is separated from the next by a transverse septum • Each metamere acts as a hydrostatic skeleton • Each metamere has longitudinal and circular muscles; longitudinal muscle contraction causes segments to shorten; circular muscle contraction causes segments to elongate • Each segment usually bears one or more chitinous bristles called setae; help anchor segments
Dr. PARVISH PANDYA’s presentation
TYPES OF METAMERISM • True & false metamerism. • Complete and incomplete metamerism. • External and internal metamerism.
Dr. PARVISH PANDYA’s presentation
Nervous System • Consists of a brain, which is connected to a pair of ventral longitudinal nerve cords, with a ganglion in each segment (metameric)
Circulatory System • Closed circulatory system, in which the blood is always enclosed within blood vessels that run the length of the body and branch to every segment • Several hearts (5 in earthworms) are used to pump blood through the closed circuit Dr. PARVISH PANDYA’s presentation
Excretory System • Consists of paired (metameric) metanephridia • Excretory tubes with ciliated funnels that remove waste from the coelomic fluid; open to the outside via excretory pores. Note: Not all organ systems are metameric For example, the digestive system extends the length of the organism and is differentiated along its length Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Development of Metameric, Coelomic Spaces
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Internal Structures of an Earthworm Dr. PARVISH PANDYA’s presentation
Dr. PARVISH PANDYA’s presentation
Nereis
Dr. PARVISH PANDYA’s presentation
Sedentary Polychaete Lugworm
Anus Mouth
Dr. PARVISH PANDYA’s presentation
Sedentary Polychaete
Amphitrite
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Earthworm Cross -Section
Dr. PARVISH PANDYA’s presentation
Dr. PARVISH PANDYA’s presentation
Class Polychaeta ("many bristles”) General Characteristics • Marine worms, including sandworms and clamworms. • Each segment is equipped with a pair of fleshy paddle-like structures parapodia; used in locomotion • Parapodia contain a large number of chitinous bristles – setae; anchor the worms
Dr. PARVISH PANDYA’s presentation
Polychaetes: General Characteristics cont.
•Prostomium is well equipped with sensory and feeding structures
Dr. PARVISH PANDYA’s presentation
Polychaetes: General Characteristics cont.
• Mouth is located just below the prostomium, but in front of the modified segments - peristomium • Digestive system includes a muscular pharynx that can be everted through the mouth • Pharynx is equipped with pincerlike jaws • Although many of the smaller polychaetes lack respiratory structures, the larger one do possess gills • Gills are usually modifications of the parapodia Dr. PARVISH PANDYA’s presentation
• serial repetition of cavities and structures • transverse septa (mesoderm) • selection? • independent regulation • e.g., hydrostatic skeleton • hyp: burrowing efficiency enhanced - competitive edge • relative energetic of cost of peristaltic waves • regional specialization - tagmatization • restriction of structures, divergence of repeated structures
Dr. PARVISH PANDYA’s presentation
Internal transport • closed • dorsal vessel is contractile (propels blood) • connected to ventral vessel at gut • hemoglobin • nephridial system • ciliated tube • uptake and removal of nitrogenous wastes • resorption of amino acids, H2O, ions
Class Polychaeta: Diversity
• Although a number of polychaetes are active predators, some are sedentary and burrow into mud or live in protective tubes in the mud • In several of these species filter feeding has evolved • A good example is the fan worm Sabella, with their feather-like head structures called radioles
Dr. PARVISH PANDYA’s presentation
Class Polychaeta: Diversity cont.
• Chaetopterus is tube dweller; lives in a U-shaped tube • Parapodia are highly modified into 3 fan-like structures that bring water into the tube • The notopodium secretes a mucous bag that traps food from the water flowing through the tube; the bag is periodically passed anteriorly toward the mouth
Dr. PARVISH PANDYA’s presentation
Class Polychaeta: Diversity cont.
• Arenicola lives in a J-shaped burrow • It employs peristaltic movements to generate a water flow • Food is filtered out from the front of the burrow
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta cont.
• Earthworms feed on vast quantities of soil that contains living and decaying organic material. • Digestive tract of the annelids shows specialization along its length: mouth, pharynx, crop (food storage), gizzard (grinding), calciferous glands (accessory glands that excrete excess calcium from the food) • Remainder of the gut is the intestine - for digestion and absorption • Its surface area is increased because of a dorsal longitudinal fold called the typhlosole
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta ("few bristles") • Many of the morphological structures are reduced when
compared to the polychaetes • Prostomium lacks sensory structures • Parapodia are absent; each segment usually contains one or more pairs of setae; used in locomotion • Aquatic forms usually have larger setae than the terrestrial forms
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta cont.
• Lack respiratory organs; gas exchanges occurs across the body wall
• Hermaphroditic, but exchange sperm during copulation • During copulation, worms join their anterior ends; held together by mucous secretions from a clitellum • After reciprocal copulation, sperm is stored in seminal receptacles • Clitellum then secretes a mucous tube that serves as a cocoon • The cocoon moves anteriorly and eggs from the oviduct and sperm from the seminal receptacles are poured into it; fertilization occurs in the cocoon • Cocoon eventually slips off the anterior end of the worm • In time, young worms emerge from the cocoon Dr. PARVISH PANDYA’s
presentation
Class Hirudinea • Body is dorso-ventrally flattened • Anterior segments are modified as a small sucker which surrounds the mouth; posterior segments form a larger sucker • Setae are completely absent • Evidence of segmentation externally, but no internal septa • There is serial repetition of many of the organs (e.g., nephridia and testes)
Dr. PARVISH PANDYA’s presentation
tubes within tubes
cuticle (collagen) epidermis glandular innervated
dorsal vessel
nephrostome G I tract septum 2 layers
ventral vessel
c.musc. l.musc.
nerve cord Dr. PARVISH PANDYA’s presentation
Tube Dwellers “Sedentaria” • straight or u-shaped • mucus, CaCO3 , sand “reefs” • modified setae • “tentacles”
Dr. PARVISH PANDYA’s presentation
gills (modified parapodia)
cilia and gills move water
Dr. PARVISH PANDYA’s presentation
THEORIES ON METAMERISM Different theories has been put forward because it occurs both in Arthropoda & Vertebrates. The various theories are as follows: 1) Fission theory 2) Pseudometamerism theory 3) Cyclomerism theory 4) Embryological theory 5) Locomotion theory Dr. PARVISH PANDYA’s presentation
SIGNIFICANCE OF METAMERISM • Locomotion • Burrowing • Reproduction • Rapid evolution of high grade of organization
Dr. PARVISH PANDYA’s presentation
REPRODUCTION • It takes place both asexually & sexually. • Asexual reproduction occurs without the fusion of male and female gametes. • Sexual reproduction takes place by the fusion of male and female gametes(sex cells).
Dr. PARVISH PANDYA’s presentation
Reproductive System • Most annelids are hermaphroditic, but they are usually cross fertilizers. • Earthworms and leeches form pairs and reciprocally fertilize one another • Some annelids (e.g. marine sandworms) are dioecious and they release eggs and sperm into the marine environment, where gametes unite to form trochophore larvae
Dr. PARVISH PANDYA’s presentation
ASEXUAL REPRODUCTION • Polychetes & aq.oligochetes show asexual reproduction. • Budding & fragmentation occurs in polychetes. • Fragmentation is divided into two types:a)Orderly and b)Spontaneous.
Dr. PARVISH PANDYA’s presentation
SEXUAL REPRODUCTION • It is shown by all the three type class • Class polychaeta e.g. Aphrodite, Amphitrite, Arenicola etc. • Class oligochaeta e.g. Pheretima. • Class hirudinea e.g. Hirudinaria.
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Earthworm Reproduction
Dr. PARVISH PANDYA’s presentation
Class Hirudinea con’t
• Leeches are hermaphroditic but engage in crossfertilization; some use hypodermic impregnation • Leeches have a clitellum and are capable of generating a cocoon
Dr. PARVISH PANDYA’s presentation
Reproduction • dioecious • epitoky • atokes bud epitokes • dispersal -> mating • trocophore larvae
Dr. PARVISH PANDYA’s presentation
Trochophore larva
Apical tuft Stomach Ciliary band
Mouth
Anus
Dr. PARVISH PANDYA’s presentation
Annelid development
Dr. PARVISH PANDYA’s presentation
The End
Dr. PARVISH PANDYA’s presentation
Dr. PARVISH PANDYA, Zoology Dept. Bhavan’s College, Andheri. Dr. PARVISH PANDYA’s presentation
Sites from which presentations have been downloaded and later editted. I am indeed thankful to them for their kindness and support : http://esg-www.mit.edu:8001/esgbio/cb/org/organelles.html http://faculty.pnc.edu/jcamp/parasit/parasit.html http://www.amnh.org/rose/hope/creatinghope/ http://www.biology.eku.edu/SCHUSTER/bio%20141/POWERPOINT %20NOTES/Intro%20to%20Protozoa_files/fullscreen.htm http://www.biosci.ohio-state.edu/~zoology/eeob405/ http://www.tulane.edu/~wiser/protozoology/pwpt/ http://www.iep.water.ca.gov/suisun/photos/wildlife.html http://www.uta.edu/biology/marshall/2343/ http://www.uta.edu/biology/faculty/faculty.html http://www.okc.cc.ok.us/biologylabs/Documents/Zoology/PowerPoint.htm http://bio.fsu.edu/ http://www.aw-bc.com/ http://www.nhm.org/ http://www.geo.cornell.edu/eas/education/course/descr/EAS302/presentations/ It is very easy to find mistakes in these presentations…..I request you to kindly rectify them and supply me the modifications needed at [email protected] Thanks a lot and have fun in teaching & learning Zoology…. Dr. PARVISH PANDYA’s presentation
Phylum Annelida
PHYLUM ANNELIDA (Annulus: Little rings) • HABIT: Free living or Ectoparasitic. • HABITAT:Sea water, fresh water, moist soil. • SIZE : It varies from 1 mm to 3 metres. • SHAPE : Body is long, cylindrical or flattened.
Dr. PARVISH PANDYA’s presentation
What is a segmented worm? •Long and narrow •Closely related to crabs and snails •Has a body built of ring-like segments
Dr. PARVISH PANDYA’s presentation
METAMERISM Metamerism is the phenomenon in which the
body of an animal is divided into anteroposterior row of similar part or sections. These sections are called as segments or metamers or somites. It involves a longitudinal division of body of a bilaterally symmetrical organism into a linear series of similar segments.
Dr. PARVISH PANDYA’s presentation
Metamerism •Have an anterior prostomium and posterior pygidium; both nonsegmented • Body is divided into a linear series of similar parts or segments, and each segment is called a metamere • The pattern of repeated segmentation is called metamerism • Each metamere is separated from the next by a transverse septum • Each metamere acts as a hydrostatic skeleton • Each metamere has longitudinal and circular muscles; longitudinal muscle contraction causes segments to shorten; circular muscle contraction causes segments to elongate • Each segment usually bears one or more chitinous bristles called setae; help anchor segments
Dr. PARVISH PANDYA’s presentation
TYPES OF METAMERISM • True & false metamerism. • Complete and incomplete metamerism. • External and internal metamerism.
Dr. PARVISH PANDYA’s presentation
Nervous System • Consists of a brain, which is connected to a pair of ventral longitudinal nerve cords, with a ganglion in each segment (metameric)
Circulatory System • Closed circulatory system, in which the blood is always enclosed within blood vessels that run the length of the body and branch to every segment • Several hearts (5 in earthworms) are used to pump blood through the closed circuit Dr. PARVISH PANDYA’s presentation
Excretory System • Consists of paired (metameric) metanephridia • Excretory tubes with ciliated funnels that remove waste from the coelomic fluid; open to the outside via excretory pores. Note: Not all organ systems are metameric For example, the digestive system extends the length of the organism and is differentiated along its length Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Development of Metameric, Coelomic Spaces
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Internal Structures of an Earthworm Dr. PARVISH PANDYA’s presentation
Dr. PARVISH PANDYA’s presentation
Nereis
Dr. PARVISH PANDYA’s presentation
Sedentary Polychaete Lugworm
Anus Mouth
Dr. PARVISH PANDYA’s presentation
Sedentary Polychaete
Amphitrite
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Earthworm Cross -Section
Dr. PARVISH PANDYA’s presentation
Dr. PARVISH PANDYA’s presentation
Class Polychaeta ("many bristles”) General Characteristics • Marine worms, including sandworms and clamworms. • Each segment is equipped with a pair of fleshy paddle-like structures parapodia; used in locomotion • Parapodia contain a large number of chitinous bristles – setae; anchor the worms
Dr. PARVISH PANDYA’s presentation
Polychaetes: General Characteristics cont.
•Prostomium is well equipped with sensory and feeding structures
Dr. PARVISH PANDYA’s presentation
Polychaetes: General Characteristics cont.
• Mouth is located just below the prostomium, but in front of the modified segments - peristomium • Digestive system includes a muscular pharynx that can be everted through the mouth • Pharynx is equipped with pincerlike jaws • Although many of the smaller polychaetes lack respiratory structures, the larger one do possess gills • Gills are usually modifications of the parapodia Dr. PARVISH PANDYA’s presentation
• serial repetition of cavities and structures • transverse septa (mesoderm) • selection? • independent regulation • e.g., hydrostatic skeleton • hyp: burrowing efficiency enhanced - competitive edge • relative energetic of cost of peristaltic waves • regional specialization - tagmatization • restriction of structures, divergence of repeated structures
Dr. PARVISH PANDYA’s presentation
Internal transport • closed • dorsal vessel is contractile (propels blood) • connected to ventral vessel at gut • hemoglobin • nephridial system • ciliated tube • uptake and removal of nitrogenous wastes • resorption of amino acids, H2O, ions
Class Polychaeta: Diversity
• Although a number of polychaetes are active predators, some are sedentary and burrow into mud or live in protective tubes in the mud • In several of these species filter feeding has evolved • A good example is the fan worm Sabella, with their feather-like head structures called radioles
Dr. PARVISH PANDYA’s presentation
Class Polychaeta: Diversity cont.
• Chaetopterus is tube dweller; lives in a U-shaped tube • Parapodia are highly modified into 3 fan-like structures that bring water into the tube • The notopodium secretes a mucous bag that traps food from the water flowing through the tube; the bag is periodically passed anteriorly toward the mouth
Dr. PARVISH PANDYA’s presentation
Class Polychaeta: Diversity cont.
• Arenicola lives in a J-shaped burrow • It employs peristaltic movements to generate a water flow • Food is filtered out from the front of the burrow
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta cont.
• Earthworms feed on vast quantities of soil that contains living and decaying organic material. • Digestive tract of the annelids shows specialization along its length: mouth, pharynx, crop (food storage), gizzard (grinding), calciferous glands (accessory glands that excrete excess calcium from the food) • Remainder of the gut is the intestine - for digestion and absorption • Its surface area is increased because of a dorsal longitudinal fold called the typhlosole
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta ("few bristles") • Many of the morphological structures are reduced when
compared to the polychaetes • Prostomium lacks sensory structures • Parapodia are absent; each segment usually contains one or more pairs of setae; used in locomotion • Aquatic forms usually have larger setae than the terrestrial forms
Dr. PARVISH PANDYA’s presentation
Class Oligochaeta cont.
• Lack respiratory organs; gas exchanges occurs across the body wall
• Hermaphroditic, but exchange sperm during copulation • During copulation, worms join their anterior ends; held together by mucous secretions from a clitellum • After reciprocal copulation, sperm is stored in seminal receptacles • Clitellum then secretes a mucous tube that serves as a cocoon • The cocoon moves anteriorly and eggs from the oviduct and sperm from the seminal receptacles are poured into it; fertilization occurs in the cocoon • Cocoon eventually slips off the anterior end of the worm • In time, young worms emerge from the cocoon Dr. PARVISH PANDYA’s
presentation
Class Hirudinea • Body is dorso-ventrally flattened • Anterior segments are modified as a small sucker which surrounds the mouth; posterior segments form a larger sucker • Setae are completely absent • Evidence of segmentation externally, but no internal septa • There is serial repetition of many of the organs (e.g., nephridia and testes)
Dr. PARVISH PANDYA’s presentation
tubes within tubes
cuticle (collagen) epidermis glandular innervated
dorsal vessel
nephrostome G I tract septum 2 layers
ventral vessel
c.musc. l.musc.
nerve cord Dr. PARVISH PANDYA’s presentation
Tube Dwellers “Sedentaria” • straight or u-shaped • mucus, CaCO3 , sand “reefs” • modified setae • “tentacles”
Dr. PARVISH PANDYA’s presentation
gills (modified parapodia)
cilia and gills move water
Dr. PARVISH PANDYA’s presentation
THEORIES ON METAMERISM Different theories has been put forward because it occurs both in Arthropoda & Vertebrates. The various theories are as follows: 1) Fission theory 2) Pseudometamerism theory 3) Cyclomerism theory 4) Embryological theory 5) Locomotion theory Dr. PARVISH PANDYA’s presentation
SIGNIFICANCE OF METAMERISM • Locomotion • Burrowing • Reproduction • Rapid evolution of high grade of organization
Dr. PARVISH PANDYA’s presentation
REPRODUCTION • It takes place both asexually & sexually. • Asexual reproduction occurs without the fusion of male and female gametes. • Sexual reproduction takes place by the fusion of male and female gametes(sex cells).
Dr. PARVISH PANDYA’s presentation
Reproductive System • Most annelids are hermaphroditic, but they are usually cross fertilizers. • Earthworms and leeches form pairs and reciprocally fertilize one another • Some annelids (e.g. marine sandworms) are dioecious and they release eggs and sperm into the marine environment, where gametes unite to form trochophore larvae
Dr. PARVISH PANDYA’s presentation
ASEXUAL REPRODUCTION • Polychetes & aq.oligochetes show asexual reproduction. • Budding & fragmentation occurs in polychetes. • Fragmentation is divided into two types:a)Orderly and b)Spontaneous.
Dr. PARVISH PANDYA’s presentation
SEXUAL REPRODUCTION • It is shown by all the three type class • Class polychaeta e.g. Aphrodite, Amphitrite, Arenicola etc. • Class oligochaeta e.g. Pheretima. • Class hirudinea e.g. Hirudinaria.
Dr. PARVISH PANDYA’s presentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Earthworm Reproduction
Dr. PARVISH PANDYA’s presentation
Class Hirudinea con’t
• Leeches are hermaphroditic but engage in crossfertilization; some use hypodermic impregnation • Leeches have a clitellum and are capable of generating a cocoon
Dr. PARVISH PANDYA’s presentation
Reproduction • dioecious • epitoky • atokes bud epitokes • dispersal -> mating • trocophore larvae
Dr. PARVISH PANDYA’s presentation
Trochophore larva
Apical tuft Stomach Ciliary band
Mouth
Anus
Dr. PARVISH PANDYA’s presentation
Annelid development
Dr. PARVISH PANDYA’s presentation
The End
Dr. PARVISH PANDYA’s presentation
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