Worms Flashcards
name 3 ways that muscles move a worm
- hydrostatic skeletons
- body cavities
- lattices
name the different worm phyla
- rotifera
- nematomorpha
- nemertea
- nematoda
- annelida
- platyhelminthes
explain the mollecular mechanism of worms, how extracellular compounds allow a worm to move in a unique way
there are charged molecular background. The like charges repel, creating a linear extension. Thus a blob will brow into a cylindar
why does NS favour the charged molecular background of a worm?
- the soft tissue is resistant
- damage repair
- they can vary in size (1mm-30m)
- can have directional movement (dorsal-ventrally, bilaterally)
worms are ____blastic. what dermal layers does this include?
triploblastic
- mesoderm
- ectoderm
- endoderm
why are hydrostatic skeletons awesome?
- water is incompressible (shape vs volume)
- soft bodied animals can re-extend their muscles due to coelom.
explain the movement of an earthworm
- longitudinal muscles contract alternately acting against the internal fluid.
- bristles grip
- peristalsis
what is peristalsis?
the manner which radial muscles can contract and relax to move the animal across a plane.
describe an acoelomate. name the phyla that have this.
- no body cavities
- muscles work against intracellular water only
- muscular waves for slow propulsion.
- platyhelminthes, nemertea
pseudocloelomates. describe and name the phyla
- lack a mesoderm layer between the cavity and the gut.
- Nematoda, Rotifera
coelomates. describe, phyla
- much more effective hydrostatic skeleton
- bounded on all sides by mesoderm
- annelida
mesoderm= what? quick think reference. how does it affect movement?
mesoderm=muscles. movement is easier
describe lattices
hydrostatic skeletons need support
- hydrostatic skeletons need support
- connective tissue lattices
- threads of collagen
- impressible in length
- wound helically
- can contract evenly, without bulging or kinking, lattice angle changes.
disadvantages to a hydrostatic skeleton
- skeleton depends upon hydration
- -confined ecologically
- -water weight
- lots of muscle required to move body
- -everywhere, not just legs
- -friction
- -locomotion inefficient
- harder nerves to control
- -precision impossible
- predation
advantages of a hydrostatic skeleton in regards to resistant to impact damage
- worms do not readily break, buckle or burst
- distortion are not harmful, and happen easily
what is the latin meaning for Rotifera?
wheel bearer
in what type of water do rotifers exist?
fresh water
how do rotifers move?
propelled. crown, wheeled corona
what is the exterior of a rotifer made of?
ciliated epidermis,
intracellular lorica.
resistant resting stage
how do rotifers reproduce?
parthenogenesis
what is another word for virgin birth?
parthenogenesis
what does Nematomorpha mean in greek? common name?
thread shape. Hair worms
where would one find a Nematomorpha? (2 places)
- fresh water damp soil
- young parasitic in arthropods
what sort of muscle do nematomorphas have? how do they move?
only longitudinal muscle.
contracting in propagated waves for locomotion
what type of lifestyle do nematomorphas have?
parasitic, definitive
Nemertea aka:
Rhynchocoela
what is the latin meaning of nemerteas?
thread, nose coelom
what are the two types of nemerteas?
proboscis worms
ribbon worms
what environment do nemerteas typically exist in?
predominantly marine
how do nemertines resemble platyhelminthes?
-triploblastic
-enclose a gut
-acoelomate
-unsegmented
-no rigid cuticle
-bounded by ciliated epidermis
-move by ciliary movement and ms squeezing
-anterior end sense organs. (eyes, brain)
PROTONEPHRIDIA
protonephridia
excretory ducts made from ectodermal intuckings
how do nemertines differ from platyhelminthes?
- proboscis
- the gut has two openings, mouth and anus
- the presence of a closed blood system
- unique cerebral sensory organs
- simple gonads, regularly repeated
- characteristically long and thin, and capable of great changes in length
Proboscis
elongated nose or snout.
- separate fluid filled cavity dorsal to the gut
- surrounded by mesoderm
- contract, retract
- food capture
- escape.
where would you find the gonads in a nemertea?
regularily repeated between lobes of gut, along the body
how do nemerteas sexually reproduce?
dioecious, hermaphroditic
greek meaning for Nematoda
thread bearer
common name for nematoda
round worms
what are the distinctive characters of nematodes?
- slender
- circular in cross-section
- triploblastic
- unsegmented
- enclosed in cuticle
- muscle longitudinal
- no blood or circulatory system
describe the cuticle of a nematoda
- many layered structure that is toughed by cross-linked protein chains
- collagen lattice for movement
- extremely resistant both mechanically and chemically
- -deserts, polar regions, digestive enzymes
do nematoda have cilia?
nope
what shape of muscle do nematoda have?
- longitudinal, not circular
- there are contractile and non-contractile regions
what was the first invertebrate to be sequenced?
C. elegans
