27 Flashcards
Deuterostomia extant phyla
Echinodermata, Hemichordata, Chordata
symmetry Echinodermata
pentaradially symmetrical
what is the armor of Echinodermata
endoskeleton made of calcium carbonate ossicles
Echinodermata ossicles
connected by mutable collagenous tissues allowing them to quickly go from rock hard
to soft and floppy without rock hard state expending energy on muscular contraction
what do Echinodermata have instead of a circulatory system
water-vascular system open to sea-water
echinoderms surfaces
oral and aboral surfaces
what are the exceptions of the echinoderm sufaces
exceptions are sea cucumbers
why was radial symmetry selected
suspension-feeding lifestyle
do other group of animals shows a 5-part radial symmetry
no other groups
what lie along ambucular tracts
5 rows of tube feet
what are tubular feet also called
podia
what give the name echinodermata
porous, calcareous, intradermal ossicles
how do ossicles originate
originates intracellularly
how are ossicles connected
ossicles are connected to each other with
collagen, and spaces between them filled
with living tissue
ways ossicles can be arranged
-3-D meshwork
-interlocking chain
-rigid test with movable spines
-small and isolated
ossicles specialized as tiny jaws
pedicellariae
-they pinch
pedicellariae
-defense
-anti-fouling
-capture prey
-can be venomous and shot at predators
how many eucoelomic systems echinoderms
five different
large eucoelomic systems echinoderms
what do they aid with
perivisceral
coelom and water-vascular system
that aid with circulation of oxygen and nutrients
what are perivisceral coelom and water-vascular system lined with?
cilia
are perivisceral coelom and water-vascular system isosmotic
no, they have added potassium
water-vascular system what does it do and how does it work
operate the tube feet through
water enters through madreporite to ring canal to 5 radial canals going down ambulacral grooves
how do tube feed extend and retract or bend
hydrostatic pressure via ampullae and retract of bend them muscles
how do suckers on tube feet work
sticky mucus, and vaccume
original function of the water
vascular system and tube feet was
who still has this
feeding
-crinoids
when an external madreporite is present
it is off-centre
echinoderms lacking
-no brain, central nervous cord or ganglia
-excretory organs
-lack specialized gas-exchange system
-lack intestines and/or anal opening
-lack image-forming eyes
instead of brain, central nervous cord or ganglia echinoderms have
arrays of nerve fibres
a nerve ring around mouth radial cords to arms
echinoderms sexes
separate
echinoderms breeding
always broadcast sperm
eggs broadcast or brooded
larvae produced by broadcast vs brooded echinoderms
broadcast have little yolk and planktotrophic
brooded yolky and lecithotrophic
development
classical deuterostomous style of
development
larva in echinoderm
1st stage called primary larva
larvae are bilaterally symmetrical
transformation to the juvenile and
adult involves
-conversion of bilateral to radial symmetry
-changes in the 3-part larval eucoelomic system
3-part larval eucoelomic system echinoderms
separate left and right pockets
changes in the 3-part larval eucoelomic system in juvenile to adult echinoderms
-parts expand or shrink asymmetrically
-some fuse to yield the adult coelomic cavities, and others disappear
gut morphology in extant echinoderms
-almost torsion-like
-gut is looped rather than linear
what di end-Permian extinction do
reduced
diversity to current five classes
Crinoidea
-basal
sea lilies, feather stars
Crinoidea diet
suspension feeders
two body forms of Crinoidea
-sea lilies are stalked
-feather stars lack stalks, can swim
Crinoidea oral surface faces
upwards
Crinoidea main arms
multiples of five
10 to 200
pinnules
ciliated ambulacral grooves
Asteroidea
sea stars
Asteroidea arms
not clearly set off from the
central disc
Asteroidea oral vs aboral face
oral surface faces substrate
aboral (with madreporite and anus
Asteroidea movement
crawl
Asteroidea feeding
opportunistic feeders
-evert their stomach
-food is liquefied with enzymes
-sucked up
Ophiuroidea
brittle stars, basket stars
oral side facing Ophiuroidea
down
arms osteroidea
clearly demarcated from the
disc; always have 5 arms
brittle stars vs basket stars arms
-basket stars curl their arms and many arm branches vertically
-brittle stars can only move their arms laterally
Ophiuroidea excretion and digestion
no intestine or anus
brittle stars diet
detritivores and predators with some
being suspension-feeders
basket stars diet
suspension-feeding’ predators
bucket-brigade’ analogy
what is bucket-brigade’ analogy
tube feet hand shit to more precise tube feet
Echinoidea
sea urchins, sand
dollars
Echinoidea body
globular or or flat, and armless
echinoidea ossicles
fused in rigid test with small holes for tube feet; have moveable spines
Echinoidea characteristics
-Aristotle’s lantern
-have pedicellariae
-spines
- covered in epithelium with muscles attached to them
Echinoidea spines
each spine can move independently
used for defense and walking
Aristotle’s lantern what is it ad what does it do
-consists of five blade-like calcareous teeth
-teeth are protruded through the mouth
-teeth sharpened by scraping against eachother
kelp and echinoidea
urchins are major enemies of kelp, destroy entire kelp forests
teeth of sea urchins
-cut holes in coral and soft rock
-very sharp
sand dollar feeding
deposit feed
how do sanddollars avoid being lifted by waves
store sand in special gut pouches
Holothuroidea
sea cucumbers
Holothuroidea symmetry
-externally bilaterally symmetrical
-internally pentaradial symmetry difficult to see except in oral tentacles
skeleton Holothuroidea
endoskeleton reduced
madreporite Holothuroidea
madreporite is internal
Holothuroidea larval transition
-do not go through the full
larval metamorphosis
-retain the bilateral symmetry of the early developmental stages
Holothuroidea gill
respiratory tree wth Cuvierian tubules branching off
Cuvierian tubules
sticky tubules can be ejected as defense
gut of Holothuroidea
gut retains its ancestral ‘torsion’
loop
how do sea cucumbers deposit-feed
branched, mucus-covered
oral tentacles passing shit to the mouth in a swiping
motion or by stuffing whole tentacle into the mouth
what is not involved in sea cucumber feeding
tube feet are not involved in feeding
what sea cucumbers have more emaborate oral tentacles
suspension feeders that are
quite sedentary
