Advanced Biology

 NOTES 12/6- 12/7/2012

Chapter 21 Variety in the World of Invertebrates

21.1 Mollusks


Mollusks are the largest group of water animals on earth

They are distinguished by a muscular food used for locomotion, a visceral hump which contains the internal organs and a mantle, a skin-like organ which covers the visceral hump, and in most species produces a calcium carbonate shell for protection

Phylum Mollusca is divided into six classes the most familiar are

Gastropods  or univalves include the snail, slug, and whelk.

Bivalves  includes the clam, mussel, oyster, and scallop.

Cephalopods includes the squid, octopus, and cuttlefish.

Bivalves: Two-shelled Mollusks

The two shells (valves) of clams scallops, oysters, and mussels give them their name of bivales:

Shells of bivalves have 3 distinct layers: hornlike layer, a crystalline middle layer, and a pearly inner layer

The inner layer some inedible oysters and clams is called mother of pearl. If an irritating substance becomes lodged in the mantle of a bivalve the animal secretes thin sheets of nacre (substance from which the pearly layer is formed around the foreign object) The sheets of nacre build up around the irritant and form a pearl.

2 shells are connected by hinges that held together by adductor muscles (only part of scallops and muscles that are not eaten

A clam uses its food for locomotion

One of the most critical activities for a bivalve is the movement of water into and out of its mantle cavity, the open chamber in which the gills are located

The  incurrent siphons takes water into the mantle cavity to the gills where oxygen and carbon dioxide is exchanged

Most of this water then passes out through the excurrent siphon

A bivalve has an open circulatory system and its blood which lacks hemoglobin is blue or colorless


Gastropods: Stomach-footed Mollusks

Shells of Gastropods are often called univalves because most of them have a single shell. Most are spiral or clockwise

Gastropods without shells. Slugs are gastropods which look like snails without shells. Some other gastropods have partial shells. Marine slugs called nudibranches include of the other most beautiful and graceful sea creatures

Economic importance. They can be pests like many land slugs and snails, which carry parasitic diseases affecting man

Body plan. Univalves have a foot, visceral hump, mantle, and usually a shell

Head structure. Some univalves have 2 pairs of tentacles on their heads. One pair is for feeling and the other pair may end in eyes. The mouth contains a radula, a rough file-like organ that scrapes food and carries it to the digestive tract. Most are herbivorous but a few are carnivorous.

Cephalopods: Head-foot Mollusks

Class Cephalopoda consists of creatures such as the octopus, squid, cuttlefish, and chambered nautilus.

Squid is a torpedo-shaped cephalopod noted for its ability to move by jet propulsion by quickly forcing water out of its siphon. When threatened the squid ejects an inky fluid into the water which confuses an attacker and allows it to escape. The giant squid, the largest invertebrate, is found in the Pacific and North Atlantic oceans. Has 10 tentacles with suckers that hold and catch fish.

Octopuses have 8 tentacles which are studded with suction cups for catching prey. The Pacific giant octopus may attain an arm spread more than 20 feet and weigh over 150 pounds. The octopus has the most complex brain of all invertebrates and thought to be the most intelligent.

Nautilus is the only cephalopod with an external shell. Each shell consists of a series of chambers arranged in a spiral. Usually about 10 inches and possesses up to 94 tentacles.

21.2 Echninoderms and Rotifers

Echinoderms: Spiny Skinned Invertebrates

Echinoderms include starfish, sea urchins, sand dollars, sea cucumbers, and brittle stars. All are spiny-skinned marine animals. Only animals with a water-vascular system, a complex system of water filled tubes that extends throughout the body.

Starfish are the best known echinoderms.

Have a body which resembles a five pointed star.

Have 5 arms or rays. At the end of each ray is a small light sensitive eyespot.

Have pincers that has 2 or 3 jaws on each pincer and is attached to the starfish by a ball and socket joint

On the underside of each ray are tube feet which are used for holding things, moving, and opening the shells of clams and oysters.

Rotifers: “Wheel Bearers”

Microscopic multi-cellular animals found in freshwater. Some are sessile while others creep on the bottom or float on the surface of the water. Have a large brain in relation to its body. Reproduce by sexual reproduction. Some of the eggs are parthenogenic (require no fertilization). These eggs are laid in the summer. The eggs laid in the winter require fertilization and have a thick shell for protection

Rotifers are important because they clean up natural wastes and provide food for small crustaceans.

Complete the 21.2 Section Review on page 451 Questions #1-3

NOTES 12/10/2012 

21.3 Coelenterates and Porifera

Coelenterates: Hollow-Intestined Invertebrates

Includes jellyfish, sea anemones, corals, and hydras

Phylum is named after the stinging cells called cnidocytes that the organisms possess.

Most live in warms waters of tropical seas, but hydras live in fresh water

Coelenterates have a saclike body with a central digestive cavity having a single opening or mouth at one end through which food enters and wastes are expelled. Have tentacles used for capturing prey. Many stinging cells used to kill or incapacitate prey and draw the prey to the mouth. Body is made up of 2 layers of cells, the ectoderm (outer layer) and the endoderm (inner layer), between the layers is a middle layer called the mesoglea which is composed of protein fibrils and sugars.

Coelenterates  are built on a form of radial symmetry and have 2 body forms – the polyp and the medusa. A polyp is a cylindrical body type which is sessile and has a mouth facing upward. A medusa is a free swimming umbrella-shaped body type which has its mouth facing downward.


The hydra is a small (less than ½ inch long) freshwater coelenterate of the polyp form

Body consists of a round base a cylindrical stalk and a central cavity with a single opening surrounded by tentacles.

Have a remarkable ability to regenerate. If cut into several pieces each piece will grow a new complete hydra.


The adult jellyfish is a free-swimming coelenterate with a medusa type of body structure.

Its mouth is located at the center of the “umbrella” and its tentacles hang down around the rim. The tentacles are equipped with cnidocytes with which it paralyzes its prey or defends itself.

Sea Anemones

Beautiful “flowers” of the ocean

Sea Anemones are comparatively large marine coelenterates which have a polyp type of body; the mouth is located at the top of the organism, surrounded by an array of stinging tentacles.

Some are only a few inches long and about ½ inch in diameter, but other species may measure as much as 2 or 3 feet across

Have grooves which extend from the slit-like mouth to the gastrovascular cavity. Cilia line these grooves and their motion creates currents which wash water down into the body cavity and between the grooves. In this way a constant supply of food and oxygen are brought to the sea anemone, these same currents sweep wastes away from the animals cells and out of its gastrovascular cavity


The coral is a colonial coelenterates.

Corals are like miniature sea anemones, except that the corals produce a lime-stone cup at the base of their bodies. This cup is a shelter in which the coral polyp can retract when disturbed.

Because corals live together in colonies, the limestone cups eventually form vast limestone structures called coral reefs.

Porifera: Sponges

There are about 4200 species of sponges which make up the phylum Porifera

Their bodies consists of only two layers, and they always grow attached to an object in the water.

Most live in the sea, only one group lives in  fresh water.

Sponges are multicellular but their cells act more or less independently of each other, and there is no coordination of their activities. Sponges are the only multicellular animals which do not have at least a rudimentary nervous system.

A sponge can be described as a hollow saclike animal with a large opening opposite of its base. The mouth opening is called an osculum but does not take in food for the sponge. Waste materials and water flow out of the osculum. An opening of this type through which water leaves an organisms is called an excurrent pore. Water enters the sponge through very small pores called incurrent pores which are located in the sides of the animal. Sponges have an inner layer of cells called the collar cells. Within the mesoglea are special cells which manufacture spicules that support the structure of the sponge.

Sponges regenerate even from a small piece.

Complete Questions #1-4 of the 21.3 (p 455) Section Review






  NOTES 11/30/2012

§Chapter 19
§Fish are coldblooded, water dwelling vertebrates with gills and scales
§19.1 Bony fish (Oseichthyes)
§Bone or No Bone
§Ichthyologists are scientists who study fish
§Fish are divided into two main groups
úFish whose skeletons are made either partially or wholly of bone
úThose whose skeletons are made of cartilage 
 2 classes of cartilaginous fish
­Sharks,  rays, and chimaeras
­Lampreys and hagfish
§Abundance and Importance
§Bony fish (class Osteichthyes) are the most abundant of all fish (95%)
§Structure of Bony Fish
§Fish have an internal skeleton
§Outer skin
§Vitals organs (such as heart, intestines, and brain)
§Have fins instead of legs
§Have gills instead of lungs
§Body regions of a fish
§Fish have 3 main body regions
§Features of fish head
§Mouth is usually located at very front of body
§Typically  the mouth is studded with many teeth. Type of teeth depends on what it eats
úHerbivorous  fish have grinding teeth
úPredatory fish have grinding teeth or spearing teeth and many have throat teeth that allow them to grip prey while swallowing
§Have a thick bony tongue that contains no taste buds
§Have taste buds spread over the outside of its body especially the head. They may even be found on the fins of some fish.
§Fish have 2 pair of nostrils that allow water to enter nasal cavities that are lined with olfactory cells that give it an excellent sense of smell


NOTES 11/19/2012

Ch 18 Reptiles and Amphibians

18.1 Reptiles: The Creeping Vertebrates

Coldblooded Animals

Coldblooded animals regulate temperature by external factors therefore their body temperature with the temperature of their surroundings

Animals whose body temperatures fluctuate in this manner are referred to as poikilotherms

Similarities among Reptiles

All true reptiles are vertebrates, are coldblooded and have dry tough skins which are covered by a protective layer of scales

Generally, all reptiles except snakes are tetrapods, having two pairs of appendages, each appendage having claws on the toes

Both adult and young reptiles breathe with lungs

Most reptiles are oviparous, reproducing my means of eggs. There are some snakes and lizards who bear live young and re called ovoviviparous.

Lizards: The most numerous reptiles

Lizards are enlongated, four-legged reptiles with a tapered tail

They live mostly in tropical regions and are found in nearly any type of habitat

The majority are less than one foot, but can be as much as 12 feet

Only 2 species of lizards are venomous the Gila monster and the Mexican beaded lizard

Many lizards are able to change their color to blend in with their surroundings

Lizards defense mechanisms

Lizards defend themselves in various ways

Some lizards will detached its tail to escape a predator. In a few weeks the tail will regrow.

Lizards also use venom, great size, speed, camouflage, and some other unusual mechanisms for defense.



Eating Habits

A few lizards are vegetarians

Some lizards eat worms and other small animals


The majority are insectivorous and therefore are important for controlling insect populations

In order to catch prey most lizards have a good sense of smell (tongue serves as an olfactory organ) and good eyesight

Complete The
18.1 Section Review
page 383 Questions # 1-8

 NOTES: 11/20/2012

?18.2 Snakes : Most Widespread Reptiles
?Snakes are legless vertebrates with long cylindrical bodies covered with dry scales
?Varying Sizes
?Snakes have a great variation in size.
?One of the smallest is around 5-6 inches and weighs only a fraction of an ounce.
?Larger snakes can be 30 feet in length and weigh over 300 pounds
?Methods of Locomotion
?The majority of snakes move by lateral (sideways) undulation; the snake bends into a series of curves as it keeps its body flat on the ground
?Rectilinear movement – many thick bodied snakes such as pythons use this straight line method of movement, the snake alternately stretches and shortens segments of its body in order to creep forward in a straight line
?Concertina movement – snakes often use this type of motion to move across smooth surfaces or to climb through trees. The snake moves the front part of its body forward, coils it slightly to anchor it and then pulls the back part forward.
?Sidewinding movement – desert dwelling snakes use this type of movement to move across sand. As the snake supports its body with its head, tail ,and two or three other points of contact, it lifts the reminder of its body off the ground and moves it sideways. The snake then moves its head and tail in line with its body and repeats the sequence.


?Scaly Skin
?Snakes bodies is covered with dry scales; these scales which may be smooth or have ridges, are thickened areas of the epidermis
NOTES Monday 11/26/2012
?Sense Organs
?Scale Covered eyes – a snake has an eye on each side of its head, giving it a wide field of vision. Most snakes are nearsighted and do not have eyelids they have transparent scales over the eyes to retain moisture
?Hearing without ears – Snakes ears are imbedded in the skull and has no external opening. They can hear vibrations and low frequency sounds. Snakes have a quadrate bone which loosely attaches the skull to the lower jaw on each side. Sound waves traveling through the ground are transmitted from the snakes lower jaws
?Sense of smell – Snakes primary smell organ is its tongue. When the snake retracts its tongue scent particles picked up by the tongue are carried to the Jacobson’s organ (two tiny cavities in the roof of its mouth which contain nerve endings that are extremely sensitive to odor) which provides a snake with an acute sense of smell
?Design for Feeding
?Small snakes eat insects; larger snakes usually ingest birds, amphibians, fish, other reptiles, and small mammals.
?Since snakes are unable to tear their food they swallow everything whole.
?A snake has double-hinged jaws which allow it to open unusually wide.
?To prevent the snakes windpipe from being blocked while its mouth and throat are full, its trachea is pushed forward over its tongue and its mouth.
?Groups of Snakes
?Herpetologists  (zoologist who study reptiles and amphibians) have identified several groups of snakes:
?Blind Snakes -  usually tiny and harmless
?Constrictors – non venomous snakes they wrap its body around its prey and it does from suffocation. 3 largest snakes pythons, anacondas, and boas are in this group but many are smaller
?Colubrids – largest group of living snakes they prey on rodents and other pests
?Elapids – snakes in this group have immovable fangs in the front of the upper jaw that are poisonous. Most venomous snake (king cobra) is in this group
?Vipers – have long immovable fangs includes pit and old world vipers includes water moccasins and rattlesnakes
?Snake Venom
?There are 2 basic types of poisons in snake venom: Neurotoxin and Hemotoxin
?A neurotoxin affects the nervous system which controls the functioning of the heart lungs and muscles.
?A hemotoxin damages blood vessels and destroys red blood cells
?Antitoxins are antibodies given to a snake bite victim that attack the toxin molecules and neutralize their effects

NOTES 11/29/12 


?18.5 Other Amphibians
?Salamanders : Amphibians with Tails
?Have moist scale-less skin and no claws
?Avoid sunlight and are seldom seen
?Move with by bending their body sharply to the left or right with each step
?Most are oviparous. The male deposits its sperm into a gelatinous structure called a spermatophore on  a leaf or stick. The female maneuvers the packet of sperm into her cloaca where the material dissolves. Internal fertilization occurs as the eggs descend through the female’s oviducts.
?Most undergo metamorphosis but a few species remain in the water as permanent larvae retain gills and other larval characteristics called paedomorphsis
?Most are fairly small but a few grow more than a foot long. The giant Japanese salamander is the largest living amphibian growing to around 5 feet in length.
?Caecilians : Limbless Amphibians
?Tropical amphibians found in warm most climates of South America Africa and southeast Asia
?Most species are underground creates and are seldom seen
?Range in size from 7 to 53 inches
?There are around 160 species of Caecilians