Platyhelminthes, Nematoda, & Annelida
gastrovascular cavity
primary organ of digestion and circulation; extensively branched into a system of canals
Coelom
a fluid-filled space between the body wall and the digestive tract; houses internal organs
Nematoda's hydrostatic skeleton
support system for the worm, bodies whip about from side to side
Flukes
take in food via their mouth, and attach themselves within the bodies of their hosts by suckers, anchors, or hooks
endoderm
the inner lining of digestive system
ectoderm
the outer layer; forms epidermis and nervous tissue
Nematoda defecation
the removal of solid wastes out the anus
peritoneum
the serous (resembling serum; of a watery nature) membrane lining the abdominal cavity
Annelida's ventral
their belly side of the body, sends branches into each segment
cuticle
thick coating protects body from digestive juices of the intestines
Planaria dorsoventral muscle bands
thin layers of muscle stretching between the dorsal and ventral surfaces of the body
Planaria parenchyma
this is all the tissue filling in the spaces between the gastrovascular cavity and the epidermis
triploblastic
three distinct embryonic tissue layers
Nematoda's complete gut
two openings to the digestive tract - a mouth and an anus
Phylum Platyhelminthes
unsegmented, soft-bodied invertebrates, the flatworms
Planaria ventral nerve cords
very thin nerves located on the ventral side of the centrally located gastrovascular cavity
evolution of a true coelom
a new body design that respositions the internal fluid and allows the development of complex tissues and organs, enables animals to evolve a wide variety of body architectures and to grow to much larger sizes
Phylum Annelida
elongated, cylindrical body divided into ringlike segments; have movable bristles called setae, and include earthworms, leeches, and polychetes
Earthworm's gizzard
grinds up the organic material with the help of soil particles, and the nutrients are absorbed in the intestine
Ascaris
has cuticle, epidermis, intestine, reproductive organs, longitudinal muscles, pseudocoelom, nerve cords, excretory canals
Class Clitellata - Earthworms
have 100 to 175 similar segments, mouth on first segment and anus on last, their pharynx enables them to suck in organic material, material passes from the pharynx via the esophagus to the gizzard, hermaphroditic
Earthworms
have five pulsating blood vessels on each side that serve as hearts, helping to pump blood, monoecious
bilateral symmetry
having a definite left and right side
Tapeworm's scolex
head region
Annelid's ganglia
masses of nerve tissue at the front end of the body; serves as their brain
Tapeworm's proglottids
a series of repetitive segments, each is a complete hermaphroditic unit
protonephridia
a tubular, excretory structure, that consists of a flame cell, and lateral canals; lead to external pores
Planaria Nervous system
anterior ganglionic "brain" and two ventral nerve cords run the length of the body
Annelida's Connections - closed circulatory system
carries blood from one segment to another, blood-like fluid is always enclosed in vessels - it never enters open sinus areas of the body, a ventral nerve cord connects the nerve centers with one another and the brain, these neural connections allow the worm to function and behave as a unified and coordinated organism
parenchyma
cellular tissue lying between the body wall and the organs of invertebrate animals lacking a coelom
Annelida body plan
complete gut, closed circulatory system, exchange oxygen and carbon dioxide with the environment through their body surfaces by diffusion, some are monoecious, and others are dioecious
Annelida's Repeated and specialized segments
composed of a series of ring-like segments running the length of the body, internally segments are divided from one another by septa
Annelid's excretory system
consists of metanephridia, ganglia, double nerve cord, and ventral
Planaria epidermis layer
covered by cilia
lateral canals
distributing water from a main canal, leads to external pores; where excess water leaves the body.
Class Clitellata - Leeches
flattened dorsoventrally, hermaphroditic, lacks internal septa, single coelom functions, large chamber, suckers at one or both ends of body
acoelomates
flatworms that have no body cavity; area between body wall and gut is filled with parenchyma cells
Annelid's hydrostatic skeleton
fluid within the coelom of each segment creates a hydrostatic, liquid-supported, skeleton that gives the segment rigidity, like an inflated balloon
Planaria
free-living, small flatworms, found in the bottom sediment of fresh water habitats, bodies are covered with cilia-propel them through the water, and have longitudinal and circular muscles
Class Turbellaria
free-living; ex: planaria
Planaria Digestive system
gastrovascular cavity, mouth only, no anus
coelomates
higher animals have a coelom that is completely lined by tissue derived from the mesoderm
Earthworm's clitellum
is a thickened band on an earthworm's body; the mucus it secretes holds the worms together during sexual intercourse
parasitic flatworms
live within the bodies of other animals
medicinal leech
long and blade-like, chitinous jaws that rasp through the skin of the victim, it secretes an anticoagulant into the wound to prevent the blood from clotting as it flows out, and its powerful sucking muscles pump the blood out quickly once the hole has been opened
mesoderm
middle layer; fills in the spaces between ectoderm and endoderm; forms muscles, reproductive organs, and excretory organs
Planaria Reproduction
monoecious or hermaphroditic
Nematoda's longitudinal muscles
no circular muscles; pull both against the cuticle and the pseudocoel, which forms a hydrostatic skeleton
Planaria Eyespots
on the head, they detect light, but don't see images
Planaria Auricles
on the side of head, tactile and chemical sensory cells
Fluke female reproductive organs
organs located in the anterior portion of the body; nearer the front, especially situated in the front of the body or nearer to the head
Fluke male reproductive organs
organs located in the posterior portion of the body; further back in position; of or nearer the rear or hind end
Class Cestoidea
parasitic flatworms, best-known species: tapeworms, have: epithelial layers that are resistant to the digestive enzymes and immune defenses of their hosts, attach to the inner walls of hosts by specialized terminal attachment organs on the scolex, and absorb food via their skin, a cuticle, and proglottieds
Class Trematoda
parasitic flatworms, i.e. flukes, have a complex life cycle with at least two hosts. The primary host, where the flukes sexually reproduce, is a vertebrate (humans), and an epithelial layers that are resistant to the digestive enzymes and immune defenses of their hosts
Phylum Nematoda
parasitic in humans and plants as well as free-living nonparasitic species in soil or water, the roundworms, they are: bilaterally symmetrical, unsegmented worms, covered by cuticle, possess only longitudinal muscles, hydrostatic skeleton, complete gut, reproduction is sexual, dioecious, ex: ascaris, hookworms, and vinegar eels
Planaria Excretory system
protonephridia with flame cells, canals, and pores remove mainly excess water from tissues and remove a very small amount of waste
longitudinal and circular muscles
push against solid surfaces to move them forward
Annelid's metanephridia
removes excess water and nitrogenous wastes
diffusion
respiration and circulation, done across the moist skin of worms
pseudocoelomates
roundworms have a coelom, but it isn't completely lined with tissue that is derived from the mesoderm
Phylum Annelida
segmented worms, ex: earthworms & leeches
Cephalization
sense organs concentrated on the anterior end; improved ability to search for food
flame cell
specialized excretory cell, removes excess water; has cilia that beat to pull in water
Earthworm's copulation
sperm cells are released from pores in specialized segments of one partner into the sperm receptacles of the other, the process going in both directions simultaneously
