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Final

BIOL 111 Study Guide - Final Guide: Nephridiopore, Ventral Nerve Cord, Seta


Department
Biology (Sci)
Course Code
BIOL 111
Professor
Suzanne Gray
Study Guide
Final

Page:
of 2
Organism
Phylum Arthropoda Class Crustaceans Crayfish
Brief
Description
Arthropoda has the most diversity out of all invertebrates
Cephilization (sensory nerves and central organs are located in the
anterior end)
Joint appendages and exoskeleton
External
Anatomy
Thick, hard chitinous cuticle that provides protection and acts as an
exoskeleton
Body region: head and the thorax (celphathornx) two regions are divided
by the cervical groove, carapace (dorsal shield that protects the head and
the thorax)
Body segments: covered in a thin chitinous layer to provide protection but
also permit locomotion
Biramous form: branches (swimmerets, maxillia, uropods, antennules)
Serial homology: similar structures in different segments (pharynx,
esophagus, crop, gizzard, intestines)
Rostrum: protective area between the two compound eyes
Movement
Abdominal extensor muscles: when these muscles contract, the
abdomen straightens
Abdominal flexor muscles: when these muscles contract, the abdomen
curls
These muscles assist in locomotion
Backward movement is facilitated by: segmented appendages, thin telson
and uropod, extensor and flexor muscles
Reproduction
Male:
1. Sperm travels through the semical ducts to the male genital pore
2. 1st swimmerets carry the sperm to the female semical receptacle
3. Fertilization is external
Female:
1. Egg travel from the ovaries through the oviduct into the female genital
pore
2. Female stores the sperm and the egg in the semical receptacle for
several months
3. Mating occurs in the spring, but sperm and egg are not released until
the spring
4. Swimmerets carry the fertilized egg for 6 weeks
5. Several weeks after this, the juvenile crayfish is ready to live
independently
Circulatory
System
Open circulatory System
Heart lies in the pericardial sinus (body cavity filled with blood)
Blood enters the heart through the ostia (tiny holes) and is then pumped
into the 7 main arteries
Blood travels to the gills, to exchange CO2 for O2 and then returns to the
heart where the blood is pumped to the rest of the body through the
arteries
Hemocyanin: oxygen-carrying pigment which contains copper
Hemocoel: cavity is filled with blood
Digestive
System
Mouth: starting point, contains specialized appendages that assist in
shredding and chewing
Digestive glands: (pair) absorption of nutrients and enzymatic digestion
occurs here
Stomach: contains mandibular muscles on the sides of the stomach that
attach to the jaw
1. Cardiac stomach: larger of the to, lined with chitinous teeth,
pulverizes and separates the food, enzymatic digestion begins here
2. Pyloric stomach: separates digestible (to the glands) and indigestible
(to the intestine) food
Respiratory
System
Contain gills at the base of the walking legs, as well as a gill chamber
(which is under the carapace)
Can respire on land for short periods of time, if their gill chambers are
filled with water
Feathery gills provide an increase in surface area when in comes to gas
diffusion
Water enters through the gills and travels into the gill chamber by the
beating of the walking legs and the gill bailer
Water is then expelled through the anterior end of the gill chamber
Nervous
System
Consists of a ventral nerve cord and a large cluster of ganglia = brain
Nerve cords run down and wrap around the esophagus and the join the
ventral nerve cord
Contain Statocysts: (sand grains and setae) perceive the direction of
gravity, therefore keep the crayfish at equilibrium
Excretory
System
Pair of green glands excrete the waste through the nephridiopore