Transcript of "10 6 all handouts animal diversity 2010 jewett edit compress2"
Arthropods are members of the Phylum Arthropoda (from Greek arthron, "joint", and
podos "foot", which together mean "jointed feet"), and include the insects, arachnids,
crustaceans, and others.
Arthropods have bilateral symmetry, meaning that if we cut the organism through its
center along its length, the two part we get will look similar to each other.
The common theory is that the origins of the phylum can be traced back to the Cambrian
Explosion, when organisms called lobopods developed harder outer structure and the
segmented parts of their bodies began to specialize in order to do a specific function
(tagmosis). Eventually, the lobopods turned into arthropods, some of the earliest of which
were the trilobites.
It is typical for an arthropod to have a cuticle (a hard substance made of proteins and
chitin) on its outer self. It serves for protection and it is considered one of the main
reasons why early arthropods were able to get out of the water (it helped against
dehydration) They usually have very well developed sensory organs such as eyes,
antennae, etc. They also have an open circulatory system – in such a system the heart
pumps hemolymph (“the blood of the arthropods”) in large places called sinuses. There
are four main types:
- cheliceriforms (which include scorpions, spiders, mites, ticks, sea
- myriapods (which include centipedes and millipedes)
- hexapods (which include insects and other six-legged organisms)
- crustaceans (which include crabs, shrimps, lobsters, etc.)
Arthropods are omnivores with a wide-ranged diet. They feed on living or dead organic
matter or may parasitize other animals. The structure of their gut and mouth parts varies
with diet. Their mouthparts are adapted according to the family and what is usual for
arthropods is to posses a pair of appendages (an appendage – additional part). Some
arthropods feed on plant sap and their mouthparts are strictly adapted to piercing and
sucking. Others might develop poison.
The exoskeleton of arthropods has regions, where chitin is thin and flexible and permits
movement, called “joints”. The muscles that allow movement are attached inside the
skeleton, rather than in the outside as in human beings.
Since joints lack exocuticle, arthropods can move appendages and flex one body segment
on another. Movement results from contraction and relaxation of striated muscle fibres.
7. Nervous System:
Arthropods’ nervous system is made up of a series of ganglia that are connected by a
ventral cord made up of two parallel connectives running along the length of the belly.
Usually, each body segment has one ganglion on each side, though some ganglia are fused
to form the brain and other large ganglia. The brain is in the head segment and is also
known as the supraesophageal ganglion. Behind the brain is the subesophageal ganglion,
made up of three pairs of fused ganglia and controls the mouthparts, the salivary glands
and certain muscles. Most arthropods have well-developed sensory organs.
Coccinellidae is a family of beetles, known variously as ladybirds, ladybugs, or lady
beetles. Lesser-used names include ladyclock, lady cow, and lady fly.
Most coccinellids are beneficial to gardeners in general, as they feed on pests.
Their range extends from North America, excluding the arctic region, down to the most
southern tip of South America. They are also found east to Europe and Asia, also
excluding the arctic regions, and south again to Africa and Australia.
Most ladybugs are predators. They eat other insects, most of which are considered pests to
Ladybugs are the most common of all beneficial insects, these predators feed on pests.
Ladybugs reproduce sexually. Each species of ladybug has its own pheromones for
attracting a mate. The ladybug goes through four stages: the egg stage, the larvae stage,
the pupa stage, and the adult ladybug stage.
9. Praying Mantis:
Its name comes from the posture of the insect, since it keeps its two front legs up in the
air. It is capable of rotating its head on 180 degrees and it uses its large eyes to scan the
environment for pray. Usually green or brown. Typically will wait in ambush until their
pray comes on good distance. Not only that it is a predator, but the female sometimes eats
the male, shortly after they mated.
Portia is a highly intelligent jumping spider. It does not use web to catch its pray, but
instead it hunts other spiders. It had developed various techniques doing that – it imitates a
caught in the web fly, it climbs on top of the nearby branches to have a better look at its
11. Human interactions:
Bad side of arthropods: spread diseases and destroy crops.
Good side of arthropods: make food (or serve as such), help pollination, destroy other
12. Fun fact – spiders are capable of living in one’s ear.
Echinodermata (Sea Stars)
1. Origin of the name - comes from Greek language. Echinos (ἐχινός), and derma (δέρμα) mean “spiny
o The origin of the phylum is from organisms with bilateral symmetry; however, only the larvae
nowadays posses this characteristic.
o The adult organisms from this phylum have radial symmetry, which is characterized by a body in 5
parts around a central axis.
3. Phylogenic tree
o Domain: Eukaryots
o Kingdom: Animalia [Metazoa]
o Main Phylum: Deuterostromia
o Phylum: Echinodermata
o Class: Asteroidea
o Clade: Sea Stars http://www.starfish.ch/cinvertebrates/seesterne.html
4. Derived Characteristics:
o The skeleton is covered with ossacles (calcite in tiny crystals), which form a flexible, but tough
covering of the exoskeleton of the organism.
o Water vascular system is a network of canals expanding to tube feet. It serves for feeding,
locomotion, and respiration. Madreporite and radial canals are part of the system.
o The ligaments, which connect the ossicles, can either be “locked” or “unlocked”. This provides the
organism with mechanical advantages.
o Symmetry and body organization of the organism
5. Taxon Relationship
o The main phylum of is Deuterostromia, which then divides into three phyla: Echinodermata,
Hemichordata, and Chordata.
o The fact that they have a common phylum makes the Echinodermata and Chordata closely related,
even though it may seem strange that mammals (including humans) are strongly connected with sea
o The most common ancestry with humans dates back to 500 million years ago.
o A taxon that incorporates 7000 marine
o The earliest representatives date from the Cambrian period
biologically: one of the most deep sea and shallow ocean groups
geologically: production of limestone from the decayed bodies of echinodermata
7. Sea stars (starfish)
o Inhabit all world’s oceans (Indian, Pacific, Arctic, Atlantic, etc)
o There are more than 1800 representatives
o Live in both shallow and deep waters (more than 6000m)
o Typical characteristics: regeneration of body parts and eating mussels
8. Reproduction http://www.biog1105-1106.org/labs/deuts/media/echinowatervasc.jpg
o Fertilization takes place in the water between gametes from the opposite sex (in an external
o When the embryos are created, they become part of the zooplankton in the water.
o The organisms gather in groups to increase their chances of reproduction, thus using environmental
and chemical signals to show their readiness for reproduction.
o Part of the body can develop into a separate and independent organism (only if part of the central
ring is in that part)
9. Nervous System
o The Echinoderms have a complex decentralized nervous system.
o Nerve plexus (a system of interlacing nerves) runs inside and under the skin of the starfish
o A central disk that includes a nerve ring is located around the esophagus and its primary function
is to give start to nerve cords
The Nerve cords are situated in the arms and ensure balance and orientation in the organism
There is a lack of sense organs, but Echinoderms are characterized by sensibility to light (eye
spots), touch (tube feet, spine), temperature, orientation and water condition
10. Digestive System
o Food are both plants and animals.
o As the mouth opens, it turns into a two layered (back and front part) stomach.
o When the food enters, enzymes are released by digestive glands to break down the food.
o The waste products are transported by a short intestine to the anus.
o Swallowing their prey (clams + oysters):
The whole prey enters the mouth
The stomach goes out of the body in order to capture the prey
In the case of shells: the prey is caught by the tube feet and the cardiac (front) stomach
enters the shell, eats out its content, which then goes to the pyloric (back) stomach where
it is further broken down
11. Human use/resources:
o Considered a delicacy in many countries around the world (Sea urchin + sea cucumber).
o Sea cucumber – used in medicine to prevent the growth of tumor cells in the body
o They are a source of lime in parts of the world where limestone is not available
o Very often Echinoderms are used for decoration
Representative Latin Habitat Location Diet Locomotion Role Human
Sea Holothuria Lives on Florida plankton, tube feet as food for food,
Cucumber sea floor or Reef, New decaying help it for others medicine
rocks Zealand organisms crawling
Sea Asteriscus Sunk pieces New bacteria, through a as food for no
Daisy Maritimus of wood Zealand, decaying series of others interaction
Bahams organisms pulsations with
on wood, movements humans
micro- of stomach
Sea Sterechinos all oceans White Sea plants, have five as food for food
Urchin Neumayeri and seas (Greece), decaying rows of tube others
Pacific matter, dead feet that
Ocean fish, function for
(New sponges, slow motion
Sea cucumber Sea Daisy Sea Urchin
1. Radial canal- canal radiating from a center, such as in a starfish
2. Madreporite- porous plate leading to the watervascular system of certain echinoderms
3. Tube feet - Extensions of the water-vascular system of echinoderms, protruding from the body and often
ending in suckers. May be used for locomotion and/or for maintaining a tight grip on prey or on the bottom.
4. Ampulla- saclike structure of the ambulacral system of starfishes
5. Podium- a platform on which a lecturer, musical conductor etc stands.
6. Digestive glands- A gland, such as the liver or pancreas, that secretes into the alimentary canal substances
necessary for digestion.
7. Central disk – an organ that includes a nerve ring and nerve cords radiating from the ring into the arms in sea
8. Feeding tentacles- the tube feet which the sea stars possess in order to catch their pray and move it to their
9. Asexual reproduction – the generation of off-spring from a single parent that occurs without the fusion of
gametes. In most cases, the offspring are genetically identical to the parent.
10. Echinoderm – radially symmetrical marine invertebrate
Handout – Mammals
Any of a class of higher vertebrates whose bodies are covered with hair, who give birth to live
young, nourishes their young with milk from ________ __________(the name mammals
comes from them), regulate their body temperature internally, have four types of well-
developed teeth and typically have four well-developed legs with toes that have nails, claws
2. Place in Evolutionary Tree
Mammals, or Mammalia are a class in the Phylum ________ and the Subphylum Vertebrata.
There are 3 Subclasses within the class Mammalia:
• Prototheria or Monotremes (2 species) (lay eggs)
• Metatheria or Marsupials (275 species) (carry their young through early infancy)
• Eutheria or placental mammals (3982 species) (carry their young in a placenta and
nurture after birth)
3. Unique Characteristics
• A female mammal uses its mammary glands to produce milk and feed it’s young
• Mammals posses hair in the form no other animal does
• The lower jaw in mammals is a single bone on either side
• Only the mammal middle ear contains 3 _________.
• In mammals the main artery leaving the heart curves to the left becoming the aortic
• mammals have a diaphragm
4. Three characteristics of life of mammals
• Mammals reproduce _______________.
• The female egg is fertilized by the man internally.
• After they give birth mammals care for their offspring for a long amount of
time. Some mammals are monotremes.
2. Life Cycle
• Mammals have three stages in their lives- _______ ______; young and ________.
• Mammals are hatched from an egg or born form their mother.
• The offspring is similar to its parents but smaller. During its life it grows and
becomes an adult who has children. This is how the cycle starts again.
3. Eating system
• A mammal has a very well developed _________ tract. It contains teeth, mouth,
stomach and small and large intestines.
• There are three types of mammals who eat different things:
- those who eat plants: ________
- those who eat meat : _________
- those who eat both plants and meat: omnivores
• Chimpanzee - Pan troglodytes; Phylum: Chordata; Class: Mammalia; Order:
Primates; Genus: Pan; They are anthropoids.
Chimpanzees are covered with black hair and weight from 40 to 60 kg, for
height from 1.3m to 1.6 m. They have opposable thumb which is used for
touching the fingerprint side of the tip of all 4 fingers with the ventral surface
of the thumb of the same hand.
They life mostly in one continent-________ and there in savannas and tropical
They are considered omnivores but they mostly eat plants such as leaves,
fruits, seeds, etc. Animals which they eat are small, for example termites.
- Chimpanzees are born from their mothers. They live both on the ground and on the
- They live in groups of adults divided by sex, in groups of offspring or like
individuals. This way of hierarchy is called fission-fussion society. Every
chimpanzee in the group has a certain role.
- Chimpanzees can attack unknown group of the same species.
- They live around 53 years and they become mature at 12.
Chimpanzees don’t like to move much, they live in one place and get used to
Chimpanzees influence negatively the plant diversity because plants are their
main food. They also interact with animals because they eat the smaller ones.
An interesting fact is that the chimpanzees are the closest relatives to human
and a chimpanzee adult is three times stronger than a person.
• Domestic Cat (Felis catus) - phylum:chordata; class:mammalia; order _________;
family:felidae; genus: Felis; a warm blooded animal; have milk glands
Probably the most popular animal in the world – found all over it;
households as well as many feral (homeless) cats (forests, grasslands,
tundra, coastal areas, agricultural land, scrublands, urban areas and
Cats feed on small prey (rodents, bird and etc.) House cats are free fed by
their owners; Usually eat meat
Move using their four legs
One of the most invasive species; Very abundant; They can lead to the
extinction of species in certain regions, especially birds;
Blind, deaf, almost without any fur start to see, taste, hear after 7
moths they are enough mature to live on their own
• African Bush Elephant (Loxodonta africana) - Phylum: chordata;
Class:mammalia; Order:proboscidae; Family:Elephantidae; it is
Can live in a diverse range of ecosystems, including forest, woodland,
savanna, grassy plains, swampy areas, and sparsely vegetated deserts
Eat roots, bark, grass, leaves, berries, seedpods, and other fruits
(herbivorous – plant eating)
Move via their four legs, can walk slowly and fast (similar to running), can
swim and cannot jump, gallop and trot
Dig holes so that they can find water to drink provide water to other
species; destroy trees and other plants, thus affecting the other species in a
An elephant is born small (115-120kg) it is defenseless and lacks many
instincts. In the process of growing up it gets more mature and gradually
obtains the needed skills and instincts to survive. The average weight of the
elephant is 4.6 tons.
8. Human interactions with mammals
• Contribute to the_____________ of some species (hunting them for other purposes
other than finding food)
• A big part of them serve as food for us (we are predators and eat meat…); we use
some of the products they produce for food, too (such as milk).
• Use their skins and fur for clothing
• We control the population of some species (create reserves)
• Use some of them for transport and for help in the farming work
1. Birds’ place in the evolutionary tree
a. Part of the phylum chordate – animals with a well defined spinal chord to support
the skeleton and body Bilateral Symmetry
b. Most closely related to reptiles – similar features with dinosaurs (skeleton, feather
development began 100 MYA)
c. The last common ancestor of birds and humans (mammals) existed 330 MYA; not
certain what it is, however, had qualities that classified it as a lizard and had
keratin - the protein which develops hair (feature only mammals have).
2. Distinctive features
a. Bilateral Symmetry
b. Plumage – mainly used for protection and flight, allow birds to recognize each
other; feathers are made out of barbs and barbules (small hairs which overlap to
produce the feather)
c. Bills and feat – Bill (mouth) is very important to birds (has the same functions as
our hands); tarsi (legs) and feet are extremely strong,
vary in length, depending on the type of bird (running or
flying), have up to 4 hallux (finger), some have 2
d. Skeleton and organ systems – skeleton has changed
throughout history to accommodate the bird’s flying
abilities, but also allows it to walk. Skeleton is filled
with compressed air, making it light and at the same
time very strong. http://platospond.com/WatsonsBlog/wp-
e. The senses – very strong eyesight, hearing close to ours, content/uploads/2009/02/image_sci_animal029
weak smell (don’t use it for anything)
3. Reproduction of Birds
a. No sex organs, during intercourse the cloacas (end of genital canal) of the two
birds meet, male throws his sperm inside the female, taking about one second
b. Female stores the sperm inside her for a period (from a week to a year, depending
on the species); grow into eggs which the females lay and care for them inside
nests(housing made out of twigs and sticks, to protect eggs and little ones)
c. When eggs hatch, some birds can take care of themselves immediately, others
need a lot of care
4. Food obtaining and Digestion
a. Birds eat all sorts of things (from fruits to insects to other birds)
b. Some birds attack their pray, others feed on the nectar of plants (extreme diversity)
c. No teeth, but have very powerful digestive system; not developed in young ones,
parents digest it for them in their mouths
d. When reaching the stomach, food is broken down and absorbed by the small
intestine, and nutrients are absorbed by the blood
5. The Nervous System of Birds
a. Brain is located inside the skull, all nerves go to and run from it, and are made of
neurons (nerve cells), which have many functions (triggering muscles, triggering
the senses, etc)
b. Unlike mammals, the birds have a more developed corpora strata, which is in
charge of the instincts of the bird
c. Birds have autonomic nervous system, which is divided into two:
i. Sympathetic – releases adrenaline and responds to danger
ii. Parasympathetic – makes sure hear and lungs work, doesn’t need signals
from the brain to do that
6. Human uses and Interaction
a. Birds have been providing humans with meat and eggs for 50000 year
b. People keep birds as pets, in some cases endangering the species
a. Emperor penguin
i. Found in Anctartica
ii. Feeds on fish and crustaceans
iii. Live ¾ of their lives under
water, so their bodies are made
to sustain the harsh conditions –
feathers work as thermo
insulators, wings have hardened
and along with webbed feet
work as paddles for swimming
iv. Major role in ecosystem is to
content/uploads/2009/10/800px- food for predators (killer whales, leopard
v. Feed for 3 months, travel and reproduce
during the harsh Antarctic winter (May – July), leave their young ones in
December, cycle repeats many times.
b. Ostrich (Struthio camelus)
i. Found only in Africa, mostly at the Southern part of the continent
ii. Feeds on plant and some insects
iii. It is unique because it walks and does not fly, having extremely strong,
long legs; it is the fastest land bird (70 km/h), lays the biggest legs, and is,
as a whole, the largest bird
iv. Role in ecosystem is to serve as food for predators (lions and leopards)
v. Live in small flocks (groups of 5-15 birds); when they breed, they lay their
eggs in one communal nest, containing up to 30 eggs, which the parents are
able to distinguish from the others
c. Bee hummingbird (Mellisuga helenae)
i. Found all over North and South America
ii. Feeds on nectar (plant liquid)
iii. Hummingbirds never walk, only fly, even for the shortest distances. Can
hover without stopping for up to 50 minutes
iv. The hummingbird has a long beak, which fits into long tubes in certain
flowers, which attract only them, and are spaced out to avoid the birds
wings; when drinking nectar from a flower to another, it carries pollen and
helps plant reproduction
v. Hatch from eggs, develop, mate, nest, lay eggs, and die
8. Fun Facts
a. Ostriches do not bury their head in the sand, however, they sleep with their necks
down, which probably created the presumption that they do
b. Ostrich meat is edible and sold in supermarkets as salami
c. A hummingbird's heart beats 615 beats in a minute.
d. Hummingbird eggs are so small that a penny would completely cover three of
March 29, 2010
spawn - produce or deposit eggs
gills - respiration organ which extracts oxygen from water
teleost (fish) - bony fish from the subclass Teleostei
sinus venosus - a large quadrangular cavity which precedes the atrium on the venous side of
the chordate heart
bulbus arteriosus - a valve or series of valves that control blood flow out of the heart
pyloric caeca - a small circular opening between the stomach and the duodenum
esophagus - the passage between the pharynx and the stomach
drag – friction
alevin - newly hatched fish; a larval salmonid that still has an attached yolk sac full of
smolt - a young salmon two or three years old, when it has acquired its silvery color; the life
stage of a salmon or trout in which it first enters the sea
1. Fishes are not a single clade. They are, however separated into three main groups:
• Agnatha: Jawless primitive fish
• Chondrichthyes: Jawed fish; cartilaginous skeletons
• OSTEICHTHYES: Bony fish; Fish with bony skeletons
2. Some fish have bilateral symmetry. However, they come in a variety of shape and sizes,
depending on the different groups they originate from.
3. General facts about Fish
• Fish live underwater
• Free swimming or laying on the bottom of the sea
• Live in both fresh and salt water
• Not a single clade
• Their way of breathing is different from that of other species due to their living
• There are three main groups of them
• They come in a plethora of shapes and sizes
• Have different ways of reproducing
Petromyzon marinus or sea
lampreys live in the Great
Lakes region in North America.
They feed off of the blood and
tissue of teleost(ray-fin fish)
fish. They live for
approximately 10 years. The
young are born in rivers, live in
the ocean as adults, and return
to the rivers to breed. The
young come out from the eggs
as blind and toothless larvae and live that way buried in mud and filter-feeding for 3-7 years.
When they grow to a certain length and metamorphosize into their parasitic form and migrate
to the sea where they live for 1-2 years, after which they go back to the rivers to spawn and
each female spawns 60-70 thousand eggs . Other types of lampreys have been used for food
for a long time and have even served as the food for upper classes throughout Europe and are
still highly prized in some parts of Southwestern Europe. However, people in North America
don’t consider them as food and that’s why they are also known as pests there because
they’ve killed of many key predators and fishes of commercial use there.
The Great White Shark, Carcharodon
carcharias, can be found in coastal
surface area in all oceans. It is known as
the largest predatory fish (6m in length,
2 200 kg in weight), eating other fish
such as dolphins, porpoises, sea lions,
etc. They live 30-100 years long. Not
much is known for their life cycle other
than that that they regularly migrate.
Birth of offspring has never been
observed, but it’s believed that they give
birth to 2-14 babies. Have no natural enemies other than humans. Although they don’t have a
big commercial value, fishing for these shark has become a popular sport. They are thought of
to be resistant to cancer and other diseases, but that is rejected by most scientists. They have
become a great tourist attraction and that’s why tourists dive in steel cages to observe them.
Usually, great white sharks don’t attack humans unless they are provoked but even if they do,
most times it isn’t fatal.
Latin name: Oncorhynchus
Common name: Pacific Salmon
Habitat: Pacific Oceans; Great Lakes
Food range: depends on the region of habitat and on
the specific salmon species; in general: smaller fishes
and organisms like zooplankton, invertebrates (larval
and adult), herring, pelagic amphipods and krill.
Life cycle: anadromous which means that they are born in fresh water then migrate and spend
their entire lives in the saltwater oceans, after which they spawn when they return to natal
rivers/lakes; also they are semparous which meants that they can spawn only once and after it,
they die. They have 6 life cycle stages which are as follows: eggs -> alevin -> fry -> smolt->
adult -> spanwer.
Locomotion: they have fins, supported by long flexible rays, which are used for the purpose
of maneuvering (the main fin is the caudal fin which helps the salmon to move forward); also,
the swim bladder is used for a buoyancy control center.
Ecological role: food for bigger fish
Human interactions: As food; as cultural symbol
Fish have a closed-loop circulatory system. The heart pumps the blood in a single loop
throughout the body. In most fish, the heart consists of four parts, including two chambers and
an entrance and exit. The first part is the sinus venosus, a thin-walled sac that collects blood
from the fish's veins before allowing it to flow to the second part, the atrium, which is a large
muscular chamber. The atrium serves as a one-way antechamber, sends blood to the third part,
ventricle. The ventricle is another thick-walled, muscular chamber and it pumps the blood,
first to the fourth part, bulbous arteriosus, a large tube, and then out of the heart. The bulbus
arteriosus connects to the aorta, through which blood flows to the gills for oxygenation.
Jaws allow fish to eat a wide variety of food, including plants and other organisms. Fish
ingest food through the mouth and break it down in the esophagus. In the stomach, food is
further digested and, in many fish, processed in finger-shaped pouches called pyloric caeca,
which secrete digestive enzymes and absorb nutrients. Organs such as the liver and pancreas
add enzymes and various chemicals as the food moves through the digestive tract. The
intestine completes the process of digestion and nutrient absorption.
How fish swim
The density of water makes it very difficult to move in, but fish can move very smoothly and
quickly. A swimming fish is relying on its skeleton for framework, its muscles for power, and
its fins for thrust and direction.
The skeleton of a fish is the most complex in all vertebrates. The skull acts as a pivot around
which the vertebral column moves.
The muscles provide the power for swimming and constitute up to 80% of the fish itself. The
muscles are arranged in multiple directions (myomeres) that allow the fish to move in any
direction. A sinusoidal wave passes down from the head to the tail. The fins provide a
platform to exert the thrust from the muscles onto the water. Drag is minimized by the
streamlined shape of the fish and a special slime fishes excrete from their skin that minimizes
frictional drag and maintains laminar (smooth) flow of water past the fish. S MOVEMENT.
Most fish possess highly developed sense organs. Nearly all daylight fish have color vision
that is at least as good as a human's. Many fish also have chemoreceptors that are responsible
for extraordinary senses of taste and smell. Although they have ears, many fish may not hear
very well. Most fish have sensitive receptors that, which detect gentle currents and vibrations,
and sense the motion of nearby fish and prey. Some fish, such as catfish and sharks, have
organs that detect low-level electric current. Other fish, like the electric eel, can produce
Fish orient themselves using landmarks and may use mental maps based on multiple
landmarks or symbols. Fish behavior in mazes reveals that they possess spatial memory and
• Domain – Eukaryotic
• Kingdom – Metazoan (animals)
• Group of phyla - Bilateria
• Subgroup of phyla – Lophotrochozoa
• Phylum – Mollusca
• Arthropods which include insects and spiders are from the
same group of phyla as Mollusca.
• Humans and Mollusca belong to the Bilateria group of phyla.
• Symmetry – bilateral
Unique Derived Characteristics of Mollusca
The species from the Mollusca clade differ from others by having
a soft body located in a a hard calcareous shell. This shell is
formed by secretions of the mantle. The mantle cavity is formed
by folds of that mantle.
Another distinctive characteristic of those organisms is the
statocyst which is a balance organ incorporated in the foot
structure of Mollusca species.
Reproduction of Mollusca
Reproduction of the organisms from the phylum is sexual. After
the egg is hatched, it becomes a swimming form called a
trochophore larva. In time it becomes longer and turns into a
veliger larva which is different in form for species from different
Locomotion of Mollusca
A bivalve closes its shells by contracting its powerful adductor
Land living mollusks, like the snail, move slowly on a flat sole called
Ocean living mollusks move or swim by jet propulsion. They propel
themselves by ejecting water from their body.
Other ocean living mollusks, like the oyster, attach themselves to
rocks or other surfaces, and can't move.
Its Latin name is Octopus vulgaris. Octopuses are found in temperate
oceans, near Britain when it’s warm, but mostly along the
northern Pacific coasts from the Sea of Japan east to Alaska and
south to California. They are commonly not very large, but they
can vary from a few centimeters to 3 or more meters and weigh
up to 25 kg. They feed mainly on crabs, lobsters, crayfish and
other mollusks. It moves by crawling or swimming, mainly using its
An octopus’s life span is not very long – about two or three
years. It starts when the female lays the eggs and then spends
one or two months “guarding” them. After the eggs hatch, they
look like very small copies of larger octopuses, but actually they
are larvae that are 3mm long. They spend some time floating with
plankton before they steadily find their place on the seabed.
Shortly after the eggs are hatched, the females might die because
of the extreme exhaustion of their birth.
The Latin name is Bivalve. Clams are found both in fresh and salt
Inhabit the coastal waters from Florida to the Gulf of St.
Lawrence, along the Gulf of Mexico to the Yucatan Peninsul, and
South Carolina. A bivalve is characterized by possessing two
shells secreted by a mantle that extends in a sheet on either side
of the body. The oldest part of the shell, the umbo, can be
recognized as a large hump on the anterior end of the dorsal side
of each shell. The umbo extends as the baby clam grows and at
some point a shell and a foot develop, too. The next stage in the
life of the clam is the reproduction one when spawning process
occurs – the female clam lets her eggs into the water and the
male lets his sperm out, too.
Clams are filter feeders that eat plankton using currents set up by
cilia on their gills to bring in food particles, usually microscopic
algae. The major role of clams in the ecosystems where they are
found in performed by the Glochidia, larva in fresh water, which
can be serious pests of freshwater fish.
The clam's foot is used to dig down into the sand, and pair of long
siphons that extrude from the clam's mantle out the side of the
shell reach up to the water above.
The scientific name is Gastropods. Most gastropods have a
single, usually spirally coiled shell into which the body can be
withdrawn. Many of the snails have an operculum. Gastropods are
the largest group of molluscs - 40,000 species which are over
80% of living molluscs. Snails have a muscular foot which is used
for "creeping". In some, it is modified for swimming or burrowing.
As it moves, the snail releases a slippery slime which makes
easier the movement. It would take a snail moving at top speed
more than a day to move from one end of an American football
field (110m/360 feet) to the other. There are three types of snails
when looking into habitat – land snail, freshwater snail and marine
snail. Marine snails constitute the majority of snail species. They
have the greatest biodiversity. Snails can be found in a wide range
of environments including ditches, deserts, and the greatest
depths of the sea.
Land snails eat primarily dying plants or fruits and living plants.
Freshwater snails eat remains of dead animals and plants. The
eaten food is sorted and goes to the stomach. There it is digested
and the parts that are not digested are excreted.
Snails and other mollusca are vital to healthy ecosystems.
For instance, land snails provide food for some small mammals
and birds and recycle forest nutrients. Freshwater snails also
provide food for fish and are also important recyclers of plant and
animal waste, which keeps water clean. Some species of snails,
such as abalones and some land snails, are edible.
Interaction of molluscs with humans
• We eat Mussel and oyster beds, clam-flats and other
• The oldest form of money known is that of the seashell.
• Shells have been ground up for use in potions
• Man has long been inspired by the graceful symmetry and
beauty of shells.
• Dyes made from molluscs were used to beautify clothing and
other items made from cloth.
• Shells have had an indirect influence in advancing on Industry
• The collection and study of shells, whether by amateurs or
professionals, is called Conchology.
• The Shell Oil Company of today, started out as a shell import
company. When the value of the shell buttons in industry fell,
they were forced to look for a better-paying commodity, and
got lucky with oil!
• Frank Lloyd Wright designed the Guggenheim Museum
around the Japanese Miracle Shell
• If an octopus loses one of its eight arms, it grows a new one
in its place!
• An octopus has three hearts. Amazing!
1. Spawning – a process by which molluscs reproduce
2. Veliger larva - a shelled larva which possesses two large,
semicircular folds bearing cilia, used in swimming and
feeding, lost as the veliger develops
3. Statocyst - sense organ found in many invertebrate animals,
consisting typically of a fluid-filled sac; functions as an organ
of balance or equilibrium
4. Calcareous - composed of, containing, or characteristic of
calcium carbonate, calcium, or limestone; chalky.
5. Mantle - a thin membrane surrounding the body of the clam
that secretes the shell
6. Operculum - a horny plate that covers the opening when the
body is in the shell
7. Adduction - a movement which brings a part of the anatomy
closer to the sagittal plane of the body
8. Gill - a respiration organ whose function is the extraction of
oxygen from water and the excretion of carbon dioxide
9. Bilateral - pertaining to the right and left sides of a structure,
10. Edible – eatable