Transcript Phylum Annelida - Berkley School District

Phylum Annelida
Phylum Annelida
Terrestrial, marine,
freshwater.
Repeating segments.
Triploblastic, true coelomate
Complete gut, closed
circulatory system, well
developed nervous system.
Respiratory organs.
Trochophore larvae in marine
forms.
Protostome.
Phylum Annelida
Class Polychaeta
Order Phyllodocida (sand worms, scale worms)
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Order Terebellida (tube worms)
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Order Terebellida
Order Sabellida (tubeworms)
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Order Terebellida
Order Sabellida (beard worms)?
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Order Terebellida
Order Sabellida
Class Clitellata
Subclass Oligochaeta (earthworms)
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Order Terebellida
Order Sabellida
Class Clitellata
Subclass Oligochaeta
Subclass Hirudinoidea (leeches)
What do Polychaetes look like?
Long, cylindrical with segments.
Head has prostomium and peristomium with mouth.
Presegmental without setae.
Last segment is the pygidium with anus.
What do Polychaetes look like?
Gut separated from body wall by coelom.
External trunk segmentation with coelomic compartments
separated inside by intersegmental septa.
Homonomous if segments are all the same, heteronomous if
segments are different.
What do Polychaetes look like?
Parapodia with bundles of setae.
Parapodia are biramous, with a
dorsal notopodium and a
ventral neuropodium.
Body form depends
on lifestyle.
How do Polychaetes support themselves and move?
Cuticle secreted by epidermis.
Longitudinal and circular
muscles along body.
Oblique muscles to parapodia.
How do Polychaetes support themselves and move?
Free-swimming and crawling species
Circular muscles maintain body form.
Longitudinal muscles in bands within each segment.
Alternately contract and relax for undulation.
Parapodia push off substratum during power stroke and
retract during recovery stroke.
How do Polychaetes support themselves and move?
Burrowing species
Circular muscles more developed for peristaltic motion.
Septa perforated so contracting a group of segments causes
others to extend.
How do Polychaetes support themselves and move?
Tube dwellers have reduced parapodia used for anchoring in tube.
Tubes used for protection and support.
Tubes made of calcium carbonate, chitin, or sediment particles.
How do Polychaetes support themselves and move?
Cerebral ganglia specialized with
different parts that innervate
different parts of the worm.
How do Polychaetes support themselves and move?
Well developed sense organs:
Complex photoreceptors.
Tactile receptors on head and parapodia.
How do Polychaetes support themselves and move?
Chemoreceptors across body.
Nuchal organs at head which are presumed chemosensory.
How do Polychaetes feed themselves?
Direct deposit feeders.
Hunters with large jaws.
How do Polychaetes feed themselves?
Selective deposit feeders with
tentacles.
Filter feeders with radioles.
How do Polychaetes feed themselves?
Foregut: buccal cavity, pharynx
(often eversible) with jaws and
teeth, and glands (poison,
enzyme, mucus).
Midgut: End of esophagus,
intestine with modified
stomach. Enzyme production.
Hindgut: Mucus added to fecal
pellets, rectum, anus.
How do Polychaetes maintain homeostasis?
Circulation and gas exchange
Respiratory organs in one part of
the body (parapodia,
branchiae in tentacle crown).
Well developed, closed
circulatory system. No real
hearts.
Respiratory pigments.
How do Polychaetes maintain homeostasis?
Osmoregulation and waste removal
Metanephridia with nephrostomes
open to coelomic fluid.
Lead to nephridioducts which
reabsorb wanted materials.
Waste released through
nephridiopore.
How do Polychaetes reproduce and develop?
Sexual reproduction
No distinct gonads. Gametes formed
from peritoneum and cells stored in
coelom.
Fertilization external.
Many free-swimming benthic polychaetes
produce epitokes.
How do Polychaetes reproduce and develop?
Holoblastic, spiral cleavage leading to
a coeloblastula. Gastrulation by
invagination or epiboly.
Trochophore larva with ciliated
prototroch and apical cilia
associated with a sense organ.
How do Polychaetes reproduce and develop?
Trochophores grow, elongate, and
segment into a polytroch larva.
4d cell divides into two teloblasts
which produce bands of mesoderm
by schizocoely.
What do Oligochaetes look like?
Freshwater, marine and terrestrial.
No parapodia and reduced number of setae.
Reduced prostomium and peristomium.
Clitellum functions in reproduction.
What do leeches look like?
Freshwater, marine and terrestrial.
No parapodia and no setae.
Even more reduced prostomium and peristomium.
Clitellum functions in reproduction.
Anterior and posterior suckers.
Dorsoventrally flattened.
Ectoparasites.
Coelom reduced to channels which functions in
circulation and waste removal.
How do Oligochaetes support themselves and move?
Thin cuticle secreted by
epidermis.
Circular and longitudinal
muscles.
Coelom segmented so each
segment separate.
How do Oligochaetes support themselves and move?
Peristaltic contractions.
Setae used to anchor. Setae
can be retracted.
Complex nervous system.
Tactile and chemo
receptors across body.
How do leeches support themselves and move?
Thin cuticle secreted by
epidermis. Many mucus
glands.
Circular, longitudinal,
dorsoventral and oblique
muscles.
Reduced coelom so muscles act
against hydrostatic tissues.
How do leeches support themselves and move?
Inchworm-like crawling.
Relatively few but large neurons.
Extremely sensitive to temperature
and vibration.
How do Oligochaetes feed and digest?
Direct deposit feeders.
Specialized areas in foregut:
Crop
Gizzard
Calciferous glands
Specialized areas in midgut:
Typhlosole
Chloragogen cells
How do leeches feed and digest?
Ectoparasites, some predators.
Suckers with three blade-like jaws.
Anesthetic and anticoagulant.
Muscular pharynx for sucking.
Large crop with cecae for storage.
How do Oligochaetes maintain homeostasis?
Respiration and circulation
Closed circulatory system
2-5 pairs of hearts with valves..
Three main longitudinal vessels.
Hemoglobin.
Gas exchange across skin.
How do Oligochaetes maintain homeostasis?
Osmoregulation and excretion
Paired metanephridia in most segments. Nephrostome in one
segment and ducts in the posterior segment.
Urea produced.
Water and salt balance.
How do leeches maintain homeostasis?
Respiration and circulation
Gas exchange across body wall.
Respiratory gases carried by vessels and chambers from
reduced coelomic space.
How do leeches maintain homeostasis?
Osmoregulation and excretion
Clustered nephrostomes called
ciliated organs.
Coelomic vessels.
How do Oligochaetes reproduce and develop?
Asexual
Transverse fission and fragmentation
How do Oligochaetes reproduce and develop?
Sexual
Simultaneous hermaphrodites.
Males: testes make sperm which are stored
in seminal vesicles. Released into sperm
ducts and out male gonopore during
copulation.
How do Oligochaetes reproduce and develop?
Sexual
Simultaneous hermaphrodites.
Females: ovaries produce eggs. Released
into coelomic space. Spermatheca store
mate’s sperm.
How do Oligochaetes reproduce and develop?
Sexual
Mutual cross-fertilization.
Cocoon formed by clitellum.
Albumin added.
Eggs from female gonopore,
sperm from spermatheca.
Sealed and deposited in soil.
Holoblastic spiral cleavage,
direct development.
How do leeches reproduce and develop?
Sexual
Simultaneous hermaphrodites with clitellum.
Mutual cross-fertilization.
Sperm released into vagina for internal
fertilization.
Cocoon formation with fertilized eggs or
embryos deposited after albumin.