ZOOLOGY –
AQUATIC MANDIBULATES
Phylum Arthropoda;
Subphylum Crustacea
THINGS YOU
NEED TO KNOW FROM THIS CHAPTER…
- Are crustaceans
biramous? What does biramous mean?
- How can you tell if an
animal is a crustacean, just by looking at it?
- How many pairs of
antennae, mandibles, and maxillae do they have?
- What are the tagmata of
crustaceans?
- What is a cephalothorax?
- What type of respiratory
system do they have?
- What type of circulatory
system do they have?
- What type of eyes do they
have?
- What is a statocyst?
- How do most crustaceans reproduce? What is the most common larval form?
- What type of feeding strategies do you
see in crustaceans?
- Know general characteristics of
crustaceans belong to classes…
- C. Malacostraca
i. Know general
characteristics about the following orders…
ii. O. Isopoda
iii. O. Amphipoda
iv. O.
Euphausiacea
1. What are
krill? Why are they important?
v. O. Decapoda
1. Why are they
the most delicious order?
- C. Branchiopoda
i. In what
order do fairy shrimp & brine shrimp belong?
ii. In what
order do tadpole shrimp belong?
iii. In what
order do clam shrimp belong?
iv. In what
order do water fleas belong?
1. Why are they
so important to other animal life?
v. How do
Branchiopods reproduce?
- C. Maxillopoda
i. What type of
eye is present in some of these animals?
ii. Know general
characteristics about the following subclasses…
1. S.
Mystacocarida
2. S. Copepoda
a. What is Calanus?
3. S.
Tantulocarida
4. S.
Branchiura (fish lice)
5. S.
Thecostraca
- C. Remipedia
- C. Cephalocarida
- C. Ostracoda
I.
Characteristics of Subphylum Crustacea
A.
Diversity
1. Over
30,000 living species and probably several times that.
2. Together, insects and crustacea compose over
_________ of all
named
animal species.
a. Crustaceans are ________________________.
1) Crustacea are mostly
________________________
with a few freshwater
species.
2) Uniramians are nearly all terrestrial
3. Probably the most abundant animals in the
world are members
of
the ________________________ genus Calanus.
B.
General Nature of
a Crustacean
1. The main distinguishing characteristic of
crustaceans is that they
have
________________________ of antennae.
2. The head also has a pair of
________________________ and
two
pairs of ________________________.
3. There is usually one pair of appendages on
each of the
additional
somites.
4. All appendages, except perhaps the first
antennae, are
biramous.
a.
Specialization of appendages is based on the basic
biramous plan
b. Crayfish appendages represent
___________________
________________________;
they have evolved a wide
variety
of walking legs, mouthparts, swimmerets, etc. from
modification
of the basic biramous appendage.
5. The tagmata are usually
________________________,
________________________,
and ________________________.
a. In some taxa, the body is only divided into a
head and
trunk.
6. In most Crustacea, one or more thoracic
segments are fused
with
the head as a ________________________.
7. The dorsal covering is the
________________________; it may
cover
most of the body or just the cephalothorax.
8. The secreted cuticle is made of chitin,
protein and calcareous
material.
C. Internal features of crustaceans.
1. Muscular and nervous systems and segmentation
show the
________________________
of annelid-like ancestors.
2. ________________________ - the major body
space in
arthropods
is not a coelom but a blood-filled cavity.
3. Respiratory System
a.
Smaller crustaceans may exchange gases across thinner
areas of cuticle on their legs, etc.
b.
Larger crustaceans use featherlike
________________________ for gas
exchange.
4. Circulatory System
a. ________________________ - there is no system
of
veins
to separate blood from interstitial fluid.
b. Hemolymph leaves the heart by
________________________
but washes through a
hemocoel
to return to the heart via
________________________.
c. The dorsal heart is the propulsive organ; it
is a
________________________-chambered
sac of striated
muscle.
d. Hemolymph is typically colorless; it contains
ameboid
cells
that may help prevent clotting.
e. ________________________ and/or
________________________
are respiratory pigments.
5. Nervous and Sensory Systems
a. The
nervous system of crustaceans has more fusion of
ganglia
than is found in other arthropods.
b. The double ventral nerve cord has a pair of
ganglia for
each
somite to control the appendages.
c. Eyes and statocysts are the largest sensory
organs.
1)
Eyes are compound, made of many units called
________________________.
a) Each ommatidium only sees a restricted
area of vision, a
________________________,
in bright light.
b) In dim light, the distal and proximal
pigments separate and
produce a continuous
image.
2)
Tactile hairs occur on the body, especially on the
chelae, mouthparts and telson.
3)
Chemical sensing of taste and smell occurs in
hairs on the antennae and mouth
4)
The ________________________ is lined with
sensory hairs that detect the
position of grains of sand
D. Reproduction, Life Cycles, and Feeding Habits
of Crustaceans
1. Diversity of Reproduction
a. Barnacles are ________________________ but
generally
cross-fertilize.
b. In some ostracods, males are scarce and
reproduction is
by
________________________.
c. Most crustaceans brood eggs in brood
chambers, in
brood sacs
attached to the abdomen, or attached to
abdominal
appendages.
d. Crayfishes develop directly without a larval
form.
e. Most crustaceans have a larva unlike the
adult in form,
and undergo
________________________.
f. The ________________________ is a common
larval
form with
uniramous first antennae, and biramous second
antennae
and mandibles that all aid in swimming.
1)
Appendages and somites are added in a series of
molts.
2. ________________________ - Molting is necessary for a
crustacean
to increase in size; the exoskeleton does not grow.
a. Ecdysis is controlled by hormones.
b. Temperature, day length or other stimuli
trigger the
central
nervous system to release hormones to begin
ecdysis.
3. Feeding Habits
a. The
same fundamental mouthparts are adapted to a wide
array
of feeding habits.
b.
________________________ feeders generate water
currents
in order to eat plankton, detritus and bacteria.
c. ________________________
consume larvae, worms,
crustaceans,
snails and fishes.
d.
________________________ eat dead animal and plant
matter.
e.
Crayfishes have a two-part stomach; a gastric mill grinds
up
food in the first compartment.
II. Brief Survey of Crustaceans
A. Class
Malacostraca
1.
This is the largest class of Crustacea and is the most diverse.
2. Order
________________________
a.
These are the only truly ________________________
crustaceans;
they also have marine and freshwater forms.
b. They
are dorsoventrally flattened, lack a carapace and
have
sessile compound eyes.
c.
Common land forms include the
________________________
bugs and _______________
bugs.
d. The
cuticle lacks the protection of insect cuticle and they
must live
in moist conditions.
3. Order
________________________
a.
Amphipods resemble isopods; they lack a carapace, have
sessile
compound eyes, and one pair of maxillipeds.
b.
However, they are compressed laterally and gills are in
the
thoracic position.
c.
Many are marine; others are beach-dwelling, freshwater or
parasitic.
4. Order
________________________
a.
This order only has about 90 species but includes the
important
ocean plankton called
“________________________.”
b.
Most are ________________________ with a light-
producing
organ called a photophore.
c.
They form a major component of the diet of
____________________________________
and of
many ________________________.
5. Order
________________________
a.
Decapods have three pairs of maxillipeds and five pairs of
walking
legs, the first forming pincers.
b.
They range from a few millimeters to the largest
arthropod,
a Japanese crab with a 4 meter leg-span.
c.
About 10,000 species of decapods are known including
________________________,
_______________________,
________________________
and ____________________.
B. Class
Branchiopoda
1.
There are four orders in this class.
a. Order Anostraca includes
________________________
and
________________________ that lack a carapace.
b. Order Notostraca includes
________________________;
the carapace forms a large
dorsal
shield.
c. Order Conchostraca includes
________________________
enclosed by a bivalved
carapace.
d. Order Cladocera includes
________________________
with a
carapace that encloses the body but not the head.
2. All
have flattened and leaf-like _______________ that are the
chief
respiratory organs.
3.
Most are freshwater organisms; cladocerans are an important
part
of the freshwater ________________________.
4.
Similar to rotifers, many use ________________________ to
rapidly
boost summer populations and then use sexual
reproduction
with the onset of unfavorable conditions.
5.
Fertilized eggs are highly resistant to cold and are critical for
winter
survival of the population.
C. Class
Maxillopoda - include a
number of groups that are descended
from a
common ancestor.
1.
When present, the eye of the nauplius is unique in structure and
is
called a ___________________________________________.
2. Subclass
________________________
a.
These tiny crustaceans (less than 0.5 mm long) live in
interstitial
water between sand grains.
b. Ten
species have been described from around the world.
3. Subclass
________________________
a.
This group is second to Malacostraca in numbers of
species.
b.
They lack a carapace and retain the simple, median,
nauplius
eye in the adult.
c.
Free-living copepods may be the dominant
________________________.
d. The
marine copepod ________________________ is the
most
abundant organism in the zooplankton by biomass
4. Subclass
________________________
a.
This group has only recently been described and it
includes
only about 12 species.
b.
They are tiny copepod-like ________________________
of
deep-sea benthic crustaceans.
5. Subclass
________________________
a.
Branchiurans lack gills; most are
________________________
of fish.
6. Subclass
________________________
a.
Thecostraca includes ______________________ in order
Thoracica
and three orders of burrowing or parasitic forms.
b.
Barnacle adults are sessile and attach directly (acorn
barnacles)
or by a stalk (goose barnacles).
c. The
head is reduced, the abdomen is absent and the
thoracic
legs are long with hairlike setae.
d. The
many-jointed ________________________ that bear
the
________________________ are extended from the
plates
to feed on small particles.
e.
Barnacles are hermaphroditic and undergo
metamorphosis
during development.
f.
They attach to the substrate by their ________________
________________________
and ____________________.
g.
They secrete calcareous plates, lose eyes and change
swimming
appendages to filtering cirri.
D. Class ________________________
1.
This class is small, with only 10 described species and all are
found
in caves connected to the sea.
E. Class
________________________
1.
This is another small class, with only nine species described.
2.
They live in coastal bottom sediments from intertidal zones to
300
meters depth.
3.
They are true ________________________ and unique in
discharging
eggs and sperm through the same duct.
F. Class ________________________
1.
Ostracods, enclosed in a bivalve carapace, resemble tiny
clams,
0.25-8.0 mm long.
2. Most
live on the bottom or climb onto plants, but some are
planktonic,
parasitic or burrowing.
3.
They are widespread in both marine and freshwater
habitats.
4.
Development is by gradual metamorphosis.