Post on 18-Jan-2018
description
Phylum Annelida the segmented worms
1st phyla we will talk about and what we will cover in the lab
today is the segmented worms Phylum Annelida Annelida from the
Latin word annelus meaning little ring All are segmented worms
Approximately 15,000 species including earthworms, freshwater
worms, leeches, and marine worms Annelida Characteristics
Triploblastic- 3 cell layers Highest level of organization: organs
Bilateral Symmetry Cephalization Eucoelomate Body Cavity
Eucoelomate
Have a true body cavity that is completely surrounded by mesoderm
ectoderm coelom mesoderm Gut endoderm Annelid Characteristics
the coelom is a closed, fluid filled cavity that surrounds the gut
the fluid within acts as a circulatory system (blood) tissue
membranes (mesenteries) suspend organs in the coelom ectoderm
Annelida Characteristics
Metamerism The body is made up of a series of repeating,
coordinated segments called metameres that are separated from one
another by septa. Each metamere contains sets of repeating organs
e.g. gut, blood vessels, nerve cord, excretory organs Metamerism
septa Metamerism Annelid Characteristics
Two part head consisting of Prostomium:fleshy lobe that overhangs
the mouth Peristomium: first body segment Annuli: circular rings
Pygidium: thelast segment;where the anus is
Clitellum:reproductivestructure annuli pygidium Annelida
Characteristics
Nervous system 2 cerebral ganglia a ventral nerve cord with 2
ganglia per metamere. In some species, sensory organssuch as eyes,
palps, and tentacleshave arisen (palps are appendages that may
ormay not be covered in cilia that helpthe worm find and pull in
food) Annelida Characteristics
Locomotion both longitudinal and circular muscles which allow them
to wiggle most have setae (chitonous bristles secreted by the
epidermis) that aid in locomotion and burrowing Skeletal System
fluid in coelom acts as a hydrostatic skeleton Annelid
Characteristics
Gas exchange mainly by diffusion through skin Class Polychaeta
often has specialized structures for gas exchange (e.g. parapodia,
gills) Annelid Characteristics
Digestive System unidirectional regional specialization (digestive
organs) Circulatory System closed circulatory system composed of
blood vessels (some of which are contractile and act as hearts)
some circulation is also accomplished by the coelomic fluid Annelid
Characteristics
Excretion excretion is accomplished by organs called nephridia
(singular nephridium) sexual Reproduction Phylum Annelida Class
Polychaeta Class Oligochaeta Class Hirudinea Class Polychaeta 1st
phyla we will talk about and what we will cover in the lab today is
Class Polychaeta All marine
This class contains 2/3 of all known Annelids Common species are
clamworms, sandworms, and lugworms have a well developed head with
specialized sense organs 1st phyla we will talk about and what we
will cover in the lab today is Class Polychaeta Commonly called
bristle worms
Have many setae (chitonous bristles secreted by the epidermis)
(Poly = many, chaeta= setae) These setae are arranged in bundleson
paddle-like appendages called parapodia 1st phyla we will talk
about and what we will cover in the lab today is setae Class
Polychaeta Parapodium 1st phyla we will talk about and what we will
cover in the lab today is setae The parapodia function in gas
exchange, locomotion, and feeding. Class Polychaeta Tagmatization
(tagmosis)
the fusion and specialization of formerly metameric segments 1st
phyla we will talk about and what we will cover in the lab today is
Class Polychaeta Many are filter-feeders with specialized
structures
1st phyla we will talk about and what we will cover in the lab
today is Class Polychaeta Many are predatory with specialized
structures
1st phyla we will talk about and what we will cover in the lab
today is Class Polychaeta 1st phyla we will talk about and what we
will cover in the lab today is Many construct their own homes out
of CaCO3 or sand debris and mucous Class Polychaeta
Reproduction
Usually dioecious (separate male and female) No permanent sex
organs; gametes are shed into coelom where they stay until time for
fertilization Fertilization is usually external in water Indirect
development trocophore larvae swims around until it grows into
adult form by addingsegments 1st phyla we will talk about and what
we will cover in the lab today is Ecology Polychaetes often have
effective defense strategies:
some have tubes to hide in some have vicious jaws some have
modified stinging setae 1st phyla we will talk about and what we
will cover in the lab today is a fireworm Ecology Some Polychaetes
have a mutualistic relationship with their host for example, many
scaleworms are found near, or in the mouth, of brittlestars,
starfish, and sea urchins. The scaleworm eats its hosts leftovers
and with its vicious jaws, it will attack any predator trying to
eat its host. 1st phyla we will talk about and what we will cover
in the lab today is Class Oligochaeta 1st phyla we will talk about
and what we will cover in the lab today is Class Oligochaeta
Habitats: terrestrial, freshwater, and marine
Have few setae (Oligo = few, chaeta = setae) Class Oligochaeta What
do earthworms eat? Usually feed on detritus
(decaying organic matter) Depends on habitat, but they can feed on
Dead leaves and plant roots Living things such as other worms,
bacteria, and fungi Decomposing remains of other animals Class
Oligochaeta Do earthworms eat dirt? Yes and No.
Earthworms consume dirt as they burrow, so yes they do swallow it.
HOWEVER, they do not get nutrients from the dirt.Their nutrients
come from decaying plant and animal remains that are in the dirt.
Class Oligochaeta Earthworms have specialized digestive system to
obtain the maximum amount of nutrients out of the detritus.
Example: pharynx, crop, gizzard, etc. Class Oligochaeta Locomotion
Circular muscle contraction
Longitudinal muscle contraction Class Oligochaeta Reproduction
Usually monoecious
Still have to have a partner. Cross-fertilize by exchanging sperm
clitellum testis Ecology Earthworms are essential soil aerators,
meaning they allow air to enter the soil. Mix the soil with their
tunnels. Worm feces are great plant food = fertilizer! 1st phyla we
will talk about and what we will cover in the lab today is Class
Hirudinea 1st phyla we will talk about and what we will cover in
the lab today is Class Hirudinea Includes leeches
usually freshwater but there are some marine and terrestrial
species no septa between metameres no setae or parapodia have 2
suckers Class Hirudinea have an extendable proboscis for feeding
Class Hirudinea usually have a fixed number of segments (34)
each metamere consists of several annuli (think accordion) 1
metamere annuli Class Hirudinea Locomotion
Lack septa between metameres, so they are incapable of moving like
Oligochaetes. Instead, they use their anterior and posterior
suckers to move. 1st phyla we will talk about and what we will
cover in the lab today is Class Hirudinea Reproduction usually
monoecious cross-fertilize by
exchanging sperm 1st phyla we will talk about and what we will
cover in the lab today is Ecology Although some leeches are
parasitic blood suckers (can be temporary or permanent), many are
predators. 1st phyla we will talk about and what we will cover in
the lab today is Ecology Leeches have been used medicinally since
the 19th century.
Currently they are used to increase blood flow following
reconstructive surgery Hirudin is a powerful anticoagulant that is
found in the salivary glands of leeches 1st phyla we will talk
about and what we will cover in the lab today is