Chapter 12-Echinoderms and Primitive Chordates Flashcards
What 3 phyla are deuterostomes?
- Echinodermata 2. Hemichordata 3. Chordata
What is the fundamental difference between deuterostomes and protostomes?
patterns of embryonic development
What animals are in Phylum Echinodermata?
sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and crinoids
T/F Most animals in Phylum Echinodermata are marine bottom-dwellers.
True
What are characteristics of echinoderms?
internal skeleton of calcareous plates called ossicles (contains spines that protrude though a thin layer of epidermis)
What kind of symmetry do juvenile echinoderms exhibit?
bilateral symmetry
What kind of symmetry do adult echinoderms exhibit?
pentaradial symmetry
How many appendages and organs do adult echinoderms generally have?
five
How many appendages and organs do adult echinoderms generally have?
five
T/F Radial symmetry is secondarily derived rather than a hold-over from more ancient phyla like cnidaria
True
What is the water vascular system?
consists of a series of water-filled canals with hollow projections form the body wall, called tube feet
What is the function of tube feet?
serve as gills for gas exchange; each major taxon usually has its own additional specialized gill; used for locomotion, feeding, or other tasks
What does the nervous system consist of in pentaradial echinoderms?
circumoral nerve ring and radial nerve that extends along each arm; sense organs are poorly developed, lack brains
What animals are in Class Crinoidea?
sea lilies and feather stars
T/F Crinoids are the ancient group of echinoderms.
True
How is the mouth facing on crinoids?
upward
Where do arms of crinoids radiate from?
cenral disc (crown)
What are features of the arms on crinoids?
each arms bears bilateral series of jointed appendages called pinnules, rows of tube feet line ambulacral grooves on oral surface of arms and pinnules
What helps feather star cling to the bottom?
cirri
What class do sea stars belong to?
Class Asteroidea
Where do hollow arms project in sea stars?
central disc
Where is the mouth located on sea stars?
centrally on underside of disc (oral surface)
Where is the anus located on sea stars?
upper, aboral surface
What is the madreporite?
button-shaped and serves as a link between the vascular system and surrounding seawater
T/F Each arm has a light-sensitive eyespot.
True
What is the ambulacral groove?
wide furrow that extends radially from the mouth along each arm
What do sea stars feed on?
bivalves such as oysters and clams
How do sea stars eat?
use arms and tube feet to pry shells apart and expose soft viscera inside; digest food extraorally (outside body) evert their stomach and engulfing their prey’s tissue before digesting it
What class do brittle stars belong to?
Class Ophiuroidea
What is unique about brittle stars?
secretive, fast, and brittle
What is the path of water through a sea star?
madreporite > stone canal > ring canal > radial canal > tube feet
What is the function of a water vascular system?
- transporting food/wastes 2. movement 3. respiration
What kinds of animals are in Class Echinoidea?
sea urchins and sand dollars
What is the shell covering echinoids called?
test
What do urchins have to help protect against predators?
spines
What do sea urchins and sand dollars eat?
algae and other organic matter
What is Aristotle’s Lantern?
highly developed producible jaw apparatus
What class are sea cucumbers a part of?
Class Holothuroidea
What is the body like in sea cucumbers?
bilateral symmetry; armless, pentaradial organization preserved as five rows of tube feet emerge at the “head” end and stop in front of posterior end; ventral surface has 3 rows of ambulacra and dorsal surface has 2; mouth surrounded by buccal podia (tentacles)
How do sea cucumbers breathe?
respiratory tree attached to cloaca, small internal chamber precedes anus
T/F Water is pumped in and out of cloaca to allow gas exchange across thin walls of tree.
True
What are the 4 features that all organisms in Phylum Chordata have?
- notochord-flexible, supporting rod 2. dorsal, hollow nerve cord 3. pharyngeal, gill slits 4. post-anal tail
What 3 subphyla do chordates belong to?
- Urochordata 2. Cephalochordata 3. Vertebrata (those with a spinal column)
What organisms belong to Subphylum Urochordata?
tunicates, sea squirts
What is a tunic?
cellulose space surrounds a sieve-like basket
Where does water enter and exit in tunicates?
enters though incurrent siphon and exits through excurrent siphon
How is the water current generated in tunicates?
cilia that line the pharynx
How do tunicates feed?
minute particles of food filtered out and passed by cilia to stomach
What organisms belong to Subphylum Cephalochordata?
cephalochordates or lancelets
What features make up cephalochordates?
lack fins and bones, poorly developed head, possess only basic organ systems
How do lancelets feed?
burrow in sediment and expose mouth and tentacles (cirri) to surface and filter out suspended food particles, water drawn into mouth by cilia, tiny food particles are then filtered by pharynx and passed to intestine, excess water leaves via pharyngeal gill slits and exits the body though an opening called the atriopore
What 8 classes belong to Subphylum Vertebrate?
Cephalospidomorphi (jawless fishes), Chondrichthyes (cartilaginous fishes), Sarcopterygii (lobe-finned fishes), Actinopterygii (ray-finned fishes), Amphibia, Reptilia, Aves, and Mammalia
What characteristics set vertebrate apart from all other organisms?
cranium and vertebral column, cephalization (concentration of nervous tissue and sensory structures in well defined head), endoskeleton (cartilage or bone), and adaptations to circulatory and respiratory systems
What are characteristics of lampreys?
eel-like design, jawless mouth, pore-like gill slits, lack of paired fins, cartilaginous endoskeleton, diphycercal caudal fin, large eyes, single nostril on top of head, seven gills on each side
T/F All lampreys are parasitic.
False: only some; non-parasitic forms do not eat as adults and have a brief lifespan
What does anadromous mean?
live in sea and then ascend freshwater rivers and streams to spawn
What are lamprey larvae called?
ammocoetes
What class do lobe-finned fishes belong to?
Class Sarcopterygii
What are characteristics of lobe-finned fishes?
bony endoskeletons and paired fins have a large, muscular lobe supported by a bony, fully articulated limb
What is the moveable bony plate covering the gills called/
operculum
Do lobe-finned fishes have a swim bladder?
yes
Sarcopterygii have only how many species present?
2 coelacanth and 6 lungfish
Which fossil led scientists to believe that amphibians evolved directly from lobe-finned fishes?
Tiktaalik
What were features of Tiktaalik?
gills and scales but neck like amphibian and limbs like amphibians but the tips of limbs are lobed fins not toes
What class do ray-finned fishes belong to?
Class Actinopterygii
Ray-finned fishes are divided into 2 groups. What are they?
chondrosteans and neoptergians
What are teleosts?
modern body fishes, most diverse group of fishes