Worms Flashcards
what type of larvae do annelids have?
Trochophores
What type of symmetry do worms have?
bilateral
What are characteristics of platyhelminthes?
Bilateral symmetry
– Three tissue layers
– Central nervous system with brain (ganglia)
(cluster of nerve tissue in head)
– Incomplete digestive tract: gut without anus
– Many are marine: free-living flatworms,
parasitic flukes, and tapeworms.
– No body cavity
– Hermaphroditic
What are characteristics of Class Turbellaria?
Free living flatworms
Mostly non-parasitic
What are characteristics of Class Monogenea?
fresh and marine parasites
external parasites of fish
simple life cycle
What are characteristics of Class Trematoda?
Internal parasites of molluscs and vertebrates
- 1 or more suckers
- Complex life cycle with two hosts
- Mollusc host first – miracidium enter host
- Vertebrate host second - cercaria dispersed and
penetrate second host
What are characteristics of Class cestoda?
tape worms
mostly hermophrodites
What are Nemertea?
Ribbon worms
What are plathelminthes?
flatworms
What are characteristics of Nemertea?
Proboscis – capture prey with venom
- Rhynchocoel – surrounds proboscis
- Reduced body cavity
-** Circulatory** system
- Many are poisonous/taste bad
- Separate mouth and anus
Why is being flat an advantage to some worms?
– **no circulatory system; **
diffuse oxygen &
nutrients directly into the cell
What is a proboscis?
structure in ribbon worms.
they compress their bodies to push out the **proboscis
What are nematoda?
roundworms
What are characteristics of nematoda?
Free living and Parasitic
- Only longitudinal muscles
- Pseudocoelom
- Circular
- Cuticle – outer case (molts case to grow)
What is the life cycle of nematoda?
Larval stages are found in fish and can be** passed** to humans if raw (or undercooked) fish is consumed
What is Spinucula?
Peanut worm
What is chaetognatha?
arrow worms
What are characteristics of chaetognatha?
No retractable anterior
* Caudal fin
* Ciliary fans
* Grasping spines (mouth)
What are the characteristics of Spiuncula?
Retractable anterior
* Introvert with tentacles – protrusible organ for
feeding
* Live in sediment, among rocks (benthic)
* Brain, central nerve cord with branches
How many plathyelminetes are there?
12,000 species
How many species of nemertea?
1,000 + species
How many species are in nematoda?
12,000 species
How many chaetognatha are there?
120 species
How many species are in sipuluca?
300
What are annelids?
segmented worms
What are the characteristics of annelida?
Metamerism (segmented)
* Coelom – fluid filled body cavity
* Locomotion via **longitudinal **and
circular muscles
What is metamerism?
- Repeating digestive glands, reproduction organs, locomotory appendages (serial homology)
- Localized contraction for movement
What is the Prostomium of a head segment?
(**front **of mouth) – head
What is Peristomium?
(surrounds mouth) – 1st “segment
What is a Pygidium
the terminal part or hind segment of the body
What is a coelom?
body cavity** between** the intestinal canal and the body wall.
What is a pseudocoelom?
the body cavity filled with fluid.
What are polychaeta?
sandworms, tube worms, clam worms
What are mobile and sedentary annelids?
Errantia (mobile/swimming)
Sedentaria (tube dwelling)
What are Clitellata
earth worms
What are the subclass of earthworms and leeches?
- Subclass: Oligochaeta – earthworms
- Subclass: Hirudinoidea - leeches
What are the types of sedentary feeders?
Suspension feeders
Filter Feeders
Deposit Feeders
How does the feather worm filter feed?
● Cilia on the tentacles direct small** food**
particles
● Small plankton swept into tubes
● If tentacles are disturbed, they will move into
tube
how does the lungworm deposit feed?
● thin-walled, jawless proboscis
o used to draw sand into the gut
o where organic matter is removed
● It continually eats the sand to create a burrow.
● This draws water into the burrow
● Filters particles from the current
What are characteristics of earthworms?
Clitellum – “collar” that forms a reproductive
cocoon during part of life cycle.
* Located near “head”
* ~8,000 species
* Hermaphrodites
What are the characteristics of leeches
Parasitic
* Anterior circumoral sucker
* Posterior ventral sucker
* ~100 marine species
What type of circulatory system do annelids have?
closed circulatory system
What are the 2 major blood vessels of annelids
dorsal and ventral: Connected by capillaries which run
through all parts of the body
How many “hearts” do annelids have and how do they function?
5:
In the head region
– Connect the ventral and dorsal blood
vessels
– Rhythmically contract
How do annelids reproduce asexually?
- can regenderate
- transverse fission: posterior half attaches itself to
substrate while anterior half continues
to move forward until two halves pull
apart
Polychaeta Sexual
Reproduction
Most male or female (dioecious)
* No specific reproductive organs,
* Conversion of several
posterior segments into
specialized reproductive
segments
* Swim to surface to release
gametes
* External fertilization
What is epitoky?
sexually immature worm is modified or transformed into a sexually mature worm
How do earthworms produce sexually?
Hermaphroditic
* Citellum secrete
cocoon
* Clitellums lined up
with** game**t-producing
sexual organs
* External feralization
* No larva stage
How do leeches reproduce sexually?
Hermaphroditic
* Sperm fertilizes egg
still in body
* Internal feralization
* No larva stage
