ecdysozoa Flashcards
what is the process of ecdysis?
molting the cuticle to grow
what is the cuticle?
a non-living outer layer of skin
what is the cuticle made of?
chitin
what are properties of the cuticle?
frequently sclerotized (hardened), but only in particular regions.
unsclerotized cuticle in between are flexible, which allows for movement
the cuticle has several layers, both living and non-living. what are all of the layers?
epicuticl
exocuticle
endocuticle
epidermis
what is the living layer of the cuticle? what is its function?
the epidermis is composed of living cells that secrete substances to the cuticle
what are the properties of the non-living cuticle?
endocuticle - within
exocuticle - outside
epicuticle - upon
what is the process ecdysozoians undergo?
molting - apolysis
what does apolysis mean?
shedding one layer of the cuticle
how does an ecdysozoian molt?
- inactive molting fluid is secreted by the epidermis
- the thin protective layer is deposited
- epidermis separates from the endocuticle
- new cuticle begins to form, thin protective layer precludes digestion
- activation of enzymes in the molting fluid make the endocuticle digested
- liquified oviducts are taken up by the epidermis
- sclerotized exocuticle is not digested
- new cuticle is ‘wrinkled’ giving it a greater surface area
- molting fluid is reabsorbed
- epicuticle is laid down
- exocuticle and epicuticle is shed through the process of ecdysis
- differentiate into exocuticle and endocuticle
why are animals that have molted larger than before?
because the new cuticle expands
how do they sclerotize (harden) their new cuticle?
secretions transported by the ducts
what is an old cuticle called?
exuviae
from the ecdysozoa species comes what animal and species?
nematodes
what are some characteristics of the phylum nematoda?
most are small
no segmentations
no appendages
no eyes
blunt at one end, pointy at the other
open circulatory system (no blood vessels)
complete digestive system (mouth and anus)
two sexes
direct development
do nematodes have to molt their non-living cuticle?
yes!
nematodes are eutelic. what does this mean?
once they hatch, growth occurs by each cell growing, not by addition of more new cells
what is an ascaris lumbricoides?
common roundworm
what is the most species rich phylum of any organism?
phylum arthropoda
phylum arthropoda are the most ___________ and _____________ ___________ group of animals
successful and ecologically important (especially decomposers and pollinators)
anthropods have tagmatization, what is this?
segmented body and jointed appendages arrange into functional units with specialized functions (division of labor)
what specialized functions does having jointed appendages give arthropods?
walking, feeding, sensory, reproduction and defense
what applies as appendages?
mouth and antenna
do arthropods have cephalization?
yes, nervous tissue becomes concentrated towards the head and there is a clear head region
what kind of circulatory system do arthropods have?
open circulatory system!
arthropods have a hemocoel filled with blood, proteins and other molecules called a?
hemolymph
how do arthropods breathe?
gills for aquatic creatures and trachea for terrestrial animals (NO LONGER DONE THROUGH DIFFUSION)
arthropods have a sclerotized cuticle made of chitin. what is its role for the arthropod?
the cuticle functions as an exoskeleton
they have to molt to the exoskeleton in order to grow (not flexible)
provides support against gravity
prevents desiccation (waxy coat prevents water loss - will not dry out)
what are three of the five major groups of arthropods?
chelicerata, myriapoda, pancrustacea
what animals are included in the chelicerata subphylum?
horseshoe crabs, spiders, mites and their relatives
cheliicerata have chelicerae. what is a chelicerae?
a feeding appendage that is operated with muscle, have 2-3 segmented piercers or fangs
chelicerata have ocelli, what is it?
simple eye (only one lens that can sense light, dark and movement)
do chelicerata have antennae?
no!
chelicerata have a cephalothorax, define it!
head that is fused with the thorax
how many limbs does a chelicerata have? what are they used for?
they have 6 pairs of limbs - four are used to walk, chelicerae, and pedipalps (additional sensory organs)
what is the specialized function of the abdomen on chelicerata?
specialized for digestion and reproduction
chelicerata split into the class arachnida. what animals are these?
spiders, mites and scorpions
what are some characteristics of the class arachnida?
ocelli - simple eyes
fluid-feeing predators - leave behind the cuticle of prey and suck out the fluids inside
separate sexes
the class arachnida specializes into the order araneae (spiders). what are the order araneae’s characteristics?
tight constriction between the cephalothorax and abdomen
chelicerae has two segments
0-4 pairs of ocelli
fluid feeding
maternal care
how do araneae (spiders) breathe?
through the tracheae or book lungs
what are book lungs?
in-folding of tissue that, when water or air goes through it, traps oxygen and air ducts remove CO2 and such from the body
how does araneae defend themselves
silk production to capture prey and poison glands
the class arachnida has another subdivision, scorpiones (scorpions). how do they get their food and eat?
pedipalps modified as grasping pinchers that crush or sting their prey to death, and they fluid-feed
the class arachnida has an order acari. what animal does this refer to?
mites
