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BIO200-Annelids and Arthropods

Terms

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Phylum Annelida
9000 species,evolved 570mya, proposed that they developed from an acoelomate flatworm ancestor.
Class Polychaeta
Clamworms
Class Oligochaeta
Earthworms
Class Hirudinea
Leeches
Metamerism
True segmental divison, external grooves, internal septa.
Hydrostatic Skeleton
body fluids act as support
Cuticle
on the surface of the annelid, a tough skin or cuticle with hard bristles
Straight Digestive Tract
A "more-or-less" straight digestive tract running from the mouth to the anus
Closed Circulatory System
blood is confined to vessels
Segmented Nervous System
nervous system consists of the brain (couple of big ganglia) and two ventral nerve cords with a pair of ganglia in each segment
ganglia
clumps of nervous tissue
parapodia
fleshy lobes for gas exchange; extended from body segments
chaetae (setae)
bristles on parapodia. these are used for locomotion
pharynx
first part of the digestive tract leading from the mouth
esophagus
tube leading from the mouth; opens in cardiac stomach
stomach/intestine
structure where digestion and absorption takes place. Found following the esophagus
ventral nerve cord
structure that transmists nerve impulses from above ganglia posteriorly along the inner ventral surface
nephridia
excretory system, (like tiny kidney tubes) one per segment
gonochoristic
seperate sexes, reproduce through copulation (physical act of mating)
clitellum
swollen glandular area that secretes a slimy material to form a cover for the eggs during reproduction
Crop
Thin-walled storage chamber for food recieved from esophagus
Gizzard
Muscular chamber that grinds the food; follows the crop
Suprapharyngeal Ganglion
A mass of nerve cells above the pharynx and connected by nerve chords and subpharygal ganglion below. Thus, the gut passes through the "brain"
Pseuohearts
five pairs of lateral blood vessels that are specialized to pump the blood
Hermaphroditic
have both male and female organs
seminal vesicles
aids in fertilization of the earthworm
somites
body segments, plainly visible in annelids. Inside the body the segments are separated by membranes called septa
esophageal caecum
secretes enzymes and increases surface area for digestion
dorsal blood vessel
structure through which blood flows anteriorly, found above the digestive tract
ventral blood vessel
structure through which blood flows posteriorly, found beneath the digestive tract
Dorsal ganglion
bilobed structure that coordinates nervous function. found in the prostomium; "the brain"
Antennae
(tentacles)...sense organs for touch and taste. found on the prostomium
Cirri
long bristles serving as organs of touch near the anus
Lateral Vessels
branched structures that supply each segment with blood. connect dorsal and ventral vessels in each segment
Segmental Ganglion
small masses of nerve cells in each segment which coordinate activities in each segment
prostomium
the first fleshy lobe of the head lying in front of the mouth. it has numerous sensory organs including eyes and tentacles or antennae
Phylum Arthropoda
1 million species evolved at least 400mya
Subphylum Trilobitomorpha
trilobites...extinct
Class Merostomata
(xiphosurida)...horshoe crabs
Class Eurypterida
sea scorpions
Class Arachnida
spiders, scorpions, mites, etc.
Subphylum Crustacea
over 26,000 species, most found in class malacostraca
Class Malacostraca
crayfish, crabs, lobsters, shrimp, etc.
Class Insecta
(hexapoda)...grashoppers, bees, fruit flies, etc.
Jointed Appendages
arthro = jointed, poda = appendages...all arthropods possess jointed appendages adaptable to a variety of habitats
Metamerism (arthropod)
consists of a series of segments...each arthropod segment bairs a pari of appendages
Regional Speciation
groups of segments have fused together to form units called the head, thorax, and abdomen.
Chitinous Exoskeleton
a tough, horny inegument called chitin covers the arthropod. (exoskeleton!)
Open Circulatory System
blood flows from a heart and arteries into blood where it bathes tissue directly
Sexual Dimorphism
males and females have different body forms. (common in arthropods)
carapace
hard shell that covers the exterior of the chephalothorax
antennae (arthropod)
sensory organs for taste and touch; found dorsally at the anterior end of the cephalothorax
chelipeds
claws or pincers for feeding and fighting, underneath the carapace of the thorax; first pair of legs
walking legs
four pairs of legs used for locomotion; found underneath the carapace of the thorax
swimmerets
five pairs of appendages that aid in respiration and reproduction, found on the ventral side of the abdomen; sexually dimorphic; males' first pair is stiff and red; female swimmerets are all identical
cardiac stomach
structure with tiny calcified teeth used for grinding food; empties into the more posterior pyloric stomach
pyloric stomach
digestive chamber where further digestion takes place; empties into intestine
intestine
structure where absorption takes place; found following the stomach
digestive gland
secretes enzymes and absorbs food.
gills
feathery structures used in gas exchange, found under the carapace and rostrum
heart
structure that pumps the blood; found dorsally in the cephalothorax
green glands
paired glands taht secrete urine (in the form of ammonia) found in the head near the mouth
gonads
structures that produce gametes (testes or ovaries); found anterior to and slightly below the heart
spiracles (arthropods)
pairs of openings into the tubular gas exchange system along the sides of the animals; found on the last two subsections of the thorax and the first eight segments of the abdomen
tympanum
structure that serves as and ear drum; found on the first segment of the abdomen
ovipositor
structure responsible for laying eggs; the last three segments of the abdomen in females
stomach
structure where further digestion takes place; found following the crop
cephalothorax
the anterior rigid part of the 2 main sections of the crayfish
abdomen
posterior jointed part of the 2 main sections of the crayfish
antennules
smaller sensory organs for taste and touch; near the antennae
mandible
sturdy jaws, surrounding the mouth
gastric caeca
six double finger-shaped pouches connecting to the gut after the crop; secretes digestive enzymes and absorbs food
thorax
one of the three main sections of the grasshopper
compound eyes
complex light-sensitive sensory organs on the dorsal side of the head.
ocelli
three sensory organs that serve as simple eyes; between the compound eyes
sensory palps
slender structures used to feel and taste food
trachae
internal gas exchange feature of the grasshopper
malpighian tubules
many tubular structures that remove waste from the body fluids and empty them into the digestive tract and eventually out the anus
cervical groove
a tansverse groove on the carapace that separates the dorsal and ventral surface
telson
central flap of tail found at the end of the abdomen
uropods
side flaps on either side of the telson
rostrum
pointed structure of anterior end of the carapace; posterior to the antennae and antennules
maxillae
small, feathery appendages that manipulate food; directly cover the mandibles
maxillipeds
large appendages that manipulate food
mandibular muscle
muscle that controls the mandible
supraesophageal ganglion
structure that coordinates nervous function ("brain"); found above the esophagus in the head
subesophageal ganglion
coordinating center for mouth, esophagus, green glands and anterior muscles
segmental ganglia
ganglia found in each segment that transmits nerve impulses from nerve cord to the organs in that segment
clypeus
broad plate that is a protective structure over the mouth
labrum
broad upper lip hinged to clypeus which functions in eating

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