DISSECTION WORKS: THE CRAYFISH
GLOSSARY
abdomen
region of the body posterior to the cephalothorax composed largely of flexor muscles
and covered by numerous jointed plates
abdominal
ganglion
large clusters of nerve cells located in each abdominal segment used to control activities
within the segment in which they are found
antennary artery
carries blood anteriorly towards the antennae; one of seven major arteries found in
the crayfish
anus
most distal end of the digestive tract (located at the ventral base of the telson)
used to discharge solid wastes from the body
Arthropoda
phylum of animals noted for their hard exoskeleton composed of chitin, jointed appendages
and including such organisms as insects, spiders and crustaceans
antenna
modified paired appendages used for touch and chemical sensation (taste; smell)
antennule
modified paired appendages used for touch, chemical sensation and balance
biramus appendages
presence of body parts that split into two parts (often at the tip or base)
bladder of nephridium
located just superior to the green gland; stores liquid wastes until it can be voided
from the body through the renal opening
cardiac stomach
most proximal portion of the stomach; receives food from the esophagus for storage
before being sent to the gastric mill for further grinding
carapace
unsegmented, anterior covering of the crustacean body composed largely of lime and
sclerotin (calcified spicules or fibers)
cephalization
concept that notes the development of a definitive head region at the anterior end
of the body
cephalothorax
fused head and thorax consisting of 13 segments covered by a hard carapace
cervical groove
jointed division between the cephalothorax and abdomen
cheliped
large, claw-like paired appendages used for grasping food and defense
compound eye
set upon short stalks in crayfish; contains over 2,000 tiny lenses used to detect
light and movement; form relatively poor visual images
Crustacea
class within the phylum Arthropoda noted for possessing biramus appendages and include
such organisms as pill bugs, Daphnia, shrimp and crayfish
digestive gland
pair of glands located posterior to the pyloric stomach that secrete enzymes necessary
for the digestion of food
dorsal abdominal artery
carries blood caudally to the extensor muscles and other structures of the abdomen
dorsal blood vessel
the "aorta" of the crayfish; transfers blood posteriorly
esophagus
connects the mouth to the cardiac portion of the stomach
extensor muscles
muscles used to straighten the abdomen after bending
eye
compound organ of sight located at the base of the rostrum
forward extension of flexors
anteriorly located muscles used to bend the abdomen; project into the cephalothorax
gastric mill
located at the posterior end of the stomach, this organ contains three small tooth-like
ossicles that are used to grind food; the "teeth" of the crayfish
gastric muscles
muscles attached to the outside of the stomach used to churn the gastric mill
gills
respiratory organs attached to the proximal (uppermost) end of the maxillae and walking
legs; sites of gas exchange in the crayfish and many other aquatic animals
green glands
pair of kidney-like structures located posterior to the antennae used to remove nitrogenous
wastes from the body while retaining salt; named for their color
heart
muscular blood pump
hepatic artery
carries blood from the heart to the digestive gland; one of seven major arteries found
in the crayfish
intestine
structure located posterior to the digestive gland and anterior to the anus; site
of most digestion
mandibles
hard, jaw-like structures, located on either side of the mouth, used to crush food
before it is passed through to the esophagus
maxilla -1st
forms what might be compared to the "upper lip" of the mouth parts; moves from side
to side thus tearing food
maxilla - 2nd
forms what might be compared to the "lower lip" of the mouth parts; moves from side
to side thus tearing food; contains the gill bailer that facilitates movement of
water over the gills during periods of lower water flow
maxilliped - 3rd
longest and largest of the appendages surrounding the mouth; useful in pushing food
into the mouth
mouth
opening into the esophagus surrounded by mandibles, maxillae and maxillipeds
nephridiopores
opening that allows the removal of nitrogenous wastes from the body
open circulatory system
type of low pressure circulation in which blood leaves vessels, bathes tissues, and
then recollects into sinuses before returning to the general circulation
opening of vas deferens
sperm duct opening at the base of the fifth walking leg
ophthalmic artery
carries blood anteriorly towards the compound eyes; one of seven major arteries found
in the crayfish
ostium (dorsal)
opening at the top of the heart that receives blood from the pericardial cavity
ostium (lateral)
opening in the side wall of the heart that receives blood from the pericardial cavity
ostium (of heart)
one of three pairs of tiny, valved openings that allow blood to enter the heart from
the pericardial cavity
ovary
site of egg production
oviduct
tube from the female ovary that ends near the base of the third walking leg; carries
eggs from their production site to the exterior of the body
pyloric stomach
distal portion of the stomach; receives ground up food from the gastric mill and strains
it for indigestible portions before sending it to the digestive gland
rectum
slight enlargement of the intestine just proximal to the anus
renal opening
opening at the base of the green gland through which nitrogen-rich wastes are expelled
from the body
renal opening of green gland
opening through which liquid wastes are voided from the body; located inferior to
the base of the antennae
rostrum
beak-like projection over the anterior-most portion of crayfish and similar organisms
useful in protecting the base of the antenna/antennule system
serial homology
principle noting the presence, on the same animal, of structures having the same embryological
origin
sperm-bearing swimmerets
first pair of male swimmerets used to transfer sperm to the female during copulation
sternal artery
branch of the dorsal abdominal; supplies much of the thoracic digestive system;
connects the dorsal to the ventral abdominal artery
stomach
sack-like structure within the anterior end of the cephalothorax that functions primarily
as a storehouse for food before it is digested
supra-esophageal ganglion
cluster of nerve cells located above the esophagus that functions as the crayfish's
brain; relatively large, bilobed structure behind the eyes
swimmerets
small structures located on the ventral surface of the abdomen useful in slow swimming
and, in the anterior pairs, modified for copulation
swimmerets 1st and 2nd
swimmerets located on the anterior, ventral abdomen used by males during copulation
to transfer sperm into the seminal receptacles of females
teeth of gastric mill
three small, tooth-like bodies located in the gastric mill used to grind larger pieces
of food into fine particles; sometimes called ossicles
telson
seventh segment of the crayfish's abdomen: useful in backward swimming
testis
tubular organ in males that produces sperm
thoracic ganglion
large clusters of nerve cells located in each thoracic segment used to control activities
within the segment in which they are located
transverse muscles
used to move appendages such as swimmerets
uropod
lateral plate, located on either side of the last abdominal segment, useful in backward
swimming
vas deferens
sperm tube passing from the testis to the base of the fifth walking leg
ventral abdominal artery
carries blood caudally to the transverse muscles and other structures of the abdomen
ventral nerve cord
roughly equivalent to the spinal cord of higher animals except that it travels along
the ventral (belly) side rather than along the dorsal (back) side; contains ganglia
and nerve cells
ventral thoracic artery
major artery located beneath the digestive organs; supplies blood to the walking legs
and other
appendages
walking legs
four pairs of biramus appendages located along the ventral cephalothorax used primarily
in slow crawling over stream bottoms