Download Unit 11 Mollusks and Echinoderms Guided Notes Molluks

Unit 11 Mollusks and Echinoderms Guided Notes
Molluks
General Characteristics of Mollusks
________________ are a very diverse group of animals that
____________________________________________________.
They contain members that are ___________________________
____________________________________________________.
However, all have _____________________________________.
These body parts are the ________________________________
____________________________________________________
_______________________________________. The _________
____________________________________________________
for those molluscs that have one.
Phylum Mollusca is made up of over 112,000 species of soft-bodied animals. These
animals generally exhibit _________________________________________________
___________________________________ as well as the three main body parts
(visceral mass, foot and mantle) introduced above. Mollusks _____________________
______________________________________________________________________
_______________________________________________. Many mollusks have
_______________________________. Nitrogenous waste is excreted through
_______________________. Mollusks have an _______________________________
with a dorsal heart and vessels. The hemocoel aids fluid return to the heart. A _______
________________________________________________________ (a flexible
tongue like strip of tissue covered with tough abrasive teeth that point backward). The
radula is used to graze, drill, or function as a poisonous dart. The nervous system has a
______________________________________________________________________
_______________________________________ with the development of the
_______________________________________ (nearly indistinguishable from
annelids). The trochophore larvae becomes the veliger larvae for swimming.
Mollusks are true ___________________________ with a reduced main body cavity
called the hemocoel. They are also Protostomes so the mouth develops first in the
embryo.
There are four main classes of Mollusks that we will study in this unit. They are
Amphineura (polyplacophora), Bivalvia, Gastropoda, and Cephalopoda.
The Chitons
The Chitons belong to Class ____________________________________________.
Chitons are ___________________________________ with a shell that is made up of
________________________________________________. They have a muscular
foot for locomotion (crawling). Chitons have a reduced head. There are about 650
species of these organisms. They can be found clinging to rocks in the intertidal zone
and use a tooth-like radula to scrape food
off
of rocks. Chitons are herbivores.
Breathing is facilitated by ____________.
........
Gastropods
Class __________________________________ has adapted
their foot so it is located on their ventral surface or belly. This is
the largest molluscan class and includes _______
_______________________________________. They are
characterized by a ______________________ with the
characteristic cone shape or no shell. Gastropods __________
__________________________________________________
__________________________________________________.
The muscular foot extends along the ventral surface of the
organism.
Gastropods undergo a process called _______________ during larval development. In
torsion the visceral mass twists 180 degrees in relation to the head. This results in the
mantle cavity, gills and anus being brought to the front of the animal. This allows the
gastropod to retract its head into its mantle cavity when threatened.
The head of gastropods contains __________________________________________
____________________________. A scraping ________________ is used to pick up
food. Slugs do not have a shell. They _______________________________________
____________________________________. They usually become active during the
cool moist part of the day. Gastropods are the only molluscan class to become
terrestrial.
Gastropods have an ________________________________________________ with a
circulatory fluid called hemolymph.
Nudibranchs (Sea Slugs) are marine gastropods that lack shells.
Nudibranch means “naked gill” and refers to the fact that gas exchange happens across
the entire surface of these animals. The images below show how these animals
maximize their surface area and their vivid colours.
Bivalves
The name ____________________________________________
_____________________________________________________
_____________________________________________________.
The mantle of a bivalve is responsible for excreting the shell to
surround and protect the body. Strong muscles hold the shell
closed in all members to the class. The muscular foot varies from
bivalve to bivalve. It is most prominent in the clam which uses its
large muscular foot to dig through the sand. Scallops can move by
jet propulsion and swim through the water escaping predators such
as sea stars. An oyster's shell will grow directly on a rock to provide
a permanent home. __________________________ but here is a scallop swimming.
Bivalves are ________________________
animals and live in the intertidal zone.
They exhibit a large visceral hump and a
muscular foot with a reduced head covered
with a thin mantle. __________________
_________________________________
_________________________________
_________________________________.
Bivalves are _______________________
and take water containing food into the
mantle cavity via the incurrent siphon and
pass it over the mouth. Excess water is
forced out through the excurrent siphon. The _________________________________
_____________________________________________________________________.
They have no radula. The general anatomy of a clam is shown above as an example of
a bivalve.
Respiration is performed by the
________________________
________________________
________________________
________________________.
This food then passes the
________________________
________________________
__________________, where it
follows an ________________
________________________.
Food is digested in the stomach
and then passes to the
__________________ for
absorption. The intestine is a
long coiled organ ending in an __________ where the waste is expelled. Also found in
the visceral mass is the heart. The _________________________________________
_________________________________ to supply it with oxygen and remove nutrients
and wastes.The diagram below shows the circulatory system of a clam. Recall,
___________________________________________________________________
with a dorsal heart and vessels.
Geoducks burrow in the sand
or amongst rocks or attach to
substrate by secreting byssal
threads. They many leap with
a foot. They have separate
sexes and external fertilization
............Mmmm oysters!
....
Clam Anatomy Review Exercises
Cephalopods
The name ____________________________________________________________
are given this term because the
_________________________
________________________
________________________.
All members of this class are
__________________. Of the
invertebrates, it can be argued
that the __________________
________________________.
This is because of their
_________________________
_________________________.
Their ability to learn and
muscular control are so
advanced that they can be
trained to open jars to obtain
food. They have quite an ________________________ that is distinctly different from
that of a human.
The cephalopods are also fast swimmers and ________________________________
___________________. To generate this propulsion they take water in slowly and expel
it so quickly that they are propelled forward. Other features of cephalopods include a
_______________________________ and a ________________ which is a toothed
tongue. Many of the animals that an octopus typically feeds on have either a shell or an
exoskeleton so the chitinous beak is necessary for feeding. For predator diversion the
cephalopods posses an ____________________
_______________________________________.
Cephalopods contain ______________________
_______________________________________
_______________________ which enable them
to change color. The octapus puts this skill to
good use as ________________________ and
the cuttlefish uses colour change to attract a mate
and warn off the competition all at the same time.
Here is a part of a TED video with a great octapus
camouflage video.
.......
Cephalopods have __________________________________________________________.
Their circulatory system is a __________________________________________, so the
circulatory fluid is contained within the vessels. Jet propulsion can be used to escape predators
by forcing water out a siphon. ____________________________________________________
____________________________________________________________________. Sexual
reproduction results in internal fertilization followed by egg laying.
Echinoderms
General Characteristics of Echinoderms
______________________________________________________________________
______________________________________________________________________
. This means that the first embryonic opening becomes the anus and the second
becomes the mouth. Because of this trait, it is thought that echinoderms are more
advanced than some of the other animals. However, ___________________________
__________________________________________. For example, their ___________
__________________________ would usually be considered more primitive than
bilateral symmetry, so it is difficult to see their relation to the vertebrates. Also,
echinoderms have ____________________________, and have a ________________
for controlling motor and sensory functions. However, when in larval form, an
echinoderm is a free swimming bilaterally symmetrical organism. It is this larval form
that scientists believe evolved into some of the prochordates that are mentioned later in
this course.
Echinoderms are fairly diverse in appearance within the phylum. Typified by the
______________________________________________________________________
________________________________________ they vary in outer appearance but
have similar internal structures . They are ____________________________________
and can be found from the intertidal zone to deep ocean waters. The digestive system is
relatively short, and digestive glands are located within the arms of the starfish, or on
the outer body wall of the other members. Digestion, however, is a bit different from
other animals, in that, much of it takes place outside the body of the starfish. The
echinoderm will put its stomach outside of its body and begin to digest its prey before it
takes it in to finish the process. They can be __________________________________.
Sex organs are also located in the arms of the starfish, and echinoderms are capable of
both _____________________________________________. External reproduction
______________________________________________________________________
______________________________________________. The regeneration properties
of starfish allow them to regrow lost limbs as well as the limb to regrow a body.
_____________________________________________________________, are found
throughout the body wall providing the echinoderm with oxygen.
The method of locomotion in the starfish is truly unique. The _____________________
_______________________________ is a network of tubes ending in
______________. An organ called an __________________ will pump water into the
tubes increasing the pressure in the tube foot causing it to expand and create suction
on a nearby surface. As the pressure on the tube foot decreases, the tube contracts
without decreasing the suction, and the starfish is pulled in that direction.
Class Asteroidea
Sea Stars have __________________________ with several
arms (5 or multiple of 5) radiating from a central body. The
_________________________________________________
________________________________________________.
The anus is at the center of the disc together with the water
intake (__________________). The upper surface is often very
colorful with ________________________________
______________________________________________
______________________________________________
____________________________________________.
Sea stars have a ________________________________
_________________________________________
_______________________________________ to
allow movement. Sea stars have ______________
________________________________________.
They have a ______________________________.
Reproduction is __________________ with most
species having separate sexes. Free swimming
larva called bipinnaria are produced. Sea stars are
________________________ and feed on and
externally digested their food. The picture below shows a sea star feeding on a bivalve.
Notice all the tube feet at work. They also have two
stomachs. Food moves first into the
________________________
______________________________.
Sea stars also exhibit the ability to regenerate body
parts......flip themselves over..even with an arm missing.
Sea Star Review Exercises
Class Crinoidea (feather stars)
Feather stars have _______________________________. The body of a typical
feather star is cup-shaped with ____________________________________________
____________________________________________________
__________________. Some have five arms while others may
have as many as 200. The
arms, called pinnules, are
coated with a sticky
substance that helps them
catch food. Cirri attached to
the underside of the body.
The mouth and their anus are
situated on the upper side of
the feather star. Below is a
video of a feather star
swimming.
........
Class Ophiuroidea (brittle stars)
_______________________________________________
___________________________________. They have
_______________________________ with a central disc and
five highly flexible arms that protrude. Unlike sea stars, there is
no replication of internal organs in each arm just one set in the
central disk.
Brittle stars have a much smaller central disc and no anus.
Wastes are eliminated through the mouth which is situated on
the underside in the center.
On the underside of the body disk there
is an opening at the base each arm on
both sides. These ten openings are
breathing and reproductive outlets.
They take in water to gain oxygen and
shed eggs or sperm into the sea.
..........
Class Echinoidea (sea urchins)
Sea urchins have a ____________________________________ body and an external
_______________________________________.
The mouth consists of a complex arrangement of muscles and plates surrounding the
circular opening. Sea urchins have a centrally located jaw (called Aristotle's lantern) with
horny teeth. The anus is located on the upper surface.
Some sea urchins have a spherical, bulb-like cloaca to
store fecal material. The cloaca protrudes from the anal
opening and can be withdrawn into the shell.
Sea urchins have movable spines of various sizes and
forms that are attached to the body. _________________
__________________________________________. They also have _____________
_____________________________________. Some of these pedicellaria are
poisonous.
........
Class Holothuroidea (sea cucumbers)
_____________________________________________________
_________________________________________ unlike most
other Echinoderms that display radial symmetry. Sea cumcubers
have a distinct dorsal and ventral side or back and bottom.
They are cucumber shaped with an elongated, muscular, and
flexible body. The mouth is at one end and the anus is at the other.
Around the mouth there are _______________________________
_______________________________- used in food collecting.
These tentacles are modified tube feet.
Here is a sea cucumber
feeding.