Invertebrates are animals that have no backbone.

MollusksMollusks

MollusksMollusks Huge phylum, wide variety of shapes/sizesHuge phylum, wide variety of shapes/sizes

~85,000 different species~85,000 different species Soft-bodied invertebratesSoft-bodied invertebrates Have bilateral symmetryHave bilateral symmetry Usually have one or two shells with organs Usually have one or two shells with organs

in a fluid filled cavityin a fluid filled cavity Most live in waterMost live in water Fossils are 500+ million years oldFossils are 500+ million years old

Mollusks’ Body PlanMollusks’ Body Plan Have a well developed head with a Have a well developed head with a

mouth and some sensory organsmouth and some sensory organs Underside is a muscular footUnderside is a muscular foot

Moves by making rhythmic Moves by making rhythmic contractionscontractions

Classification of MollusksClassification of Mollusks Classified into three common Classified into three common

groups based on shell presence, groups based on shell presence, type and foot typetype and foot type GastropodsGastropods BivalvesBivalves CephalopodsCephalopods

GastropodsGastropods Largest group of mollusksLargest group of mollusks Usually have a single shellUsually have a single shell Use a radula (a tongue-like organ Use a radula (a tongue-like organ

with rows of teeth) to get foodwith rows of teeth) to get food Have foot glands that secrete a Have foot glands that secrete a

layer of mucus for slidinglayer of mucus for sliding Includes snails, conchs, and garden Includes snails, conchs, and garden

slugsslugs

BivalvesBivalves

Have a hinged, two-part shellHave a hinged, two-part shell To open or close their shell they To open or close their shell they

either contract or relax their muscleseither contract or relax their muscles Includes clams, oysters, and scallopsIncludes clams, oysters, and scallops Well adapted for waterWell adapted for water

Clams can burrow in sandClams can burrow in sand Mussels attach themselves to a solid surfaceMussels attach themselves to a solid surface Scallops escape predators by rapidly opening Scallops escape predators by rapidly opening

and closing their shelland closing their shell

CephalopodsCephalopods Most specialized and complex Most specialized and complex

mollusks.mollusks. Include squid, octopuses, and Include squid, octopuses, and

chambered nautiluses.chambered nautiluses. Have a well developed head and Have a well developed head and

many tentacles for capturing many tentacles for capturing prey.prey.

Closed circulatory systemClosed circulatory system Moves blood through the body in a Moves blood through the body in a

series of closed vessels like humans.series of closed vessels like humans. Use jet propulsion to move at Use jet propulsion to move at

speeds of 6 m/s.speeds of 6 m/s.

ArthropoArthropodsds

An arthropod is an invertebrate with an exoskeleton, a segmented

body, and jointed legs.

There are more than 1 million kinds of arthropods on Earth.

An exoskeleton is a hard, outer covering.

Molting is to leave an exoskeleton and grow a new one.

A crustacean is an arthropod that has a hard, exoskeleton, two pairs of

antennae, and a mouth for crunching and grinding.

Crustaceans can ________ certain parts of their body.

A ___________ can re-grow its claws.

Most crustaceans live in ______ and get oxygen from the water through _________.

Gills are

EchinodermEchinodermss

* Echinoderms are __________, ________, __________, ________, ____________, and _____________.

* Echinoderm means _______________. All echinoderms have spiny skin.

•There are ______ characteristics of echinoderms.

•All echinoderms have:• Spiny skin• An internal skeleton• A five part body• A water vascular system• Tube feet

* All echinoderms have __________. Some of them have small hair-like spines, like the starfish.

* Some echinoderms have long spines, like the sea urchin.

* The internal skeleton of an echinoderm is made of _______________________.

* The water vascular system also helps an echinoderm _____.

* An echinoderm’s water vascular system is _________________________________.

* Echinoderms have __________.

* An echinoderm’s tube feet are used for _________________________________.

* Starfish are also called ___________.

* Starfish have __________ arms connected to a central body.

* On the bottom of the arms are hundreds of ___________ that look like suction cups.

* A starfish uses its tube feet to move

and to open its food.

* A starfish is able to re-grow its arms.

* Sea urchins have longer and sharper ________ that they use to protect themselves.

* Some sea urchins have ________ spines.

* Sea urchins have a mouth hidden under its body.* A sea urchin uses its five teeth to eat ____________.* A sea urchin is not very active. Sometimes, it does move slowly using its __________. When not moving it uses its feet to stick to the ocean floor.

Shape of Life – Survival Shape of Life – Survival GameGame

DVD: Episode 6 – Survival Game: MollusksDVD: Episode 6 – Survival Game: Mollusks

Mollusks’ Body PlanMollusks’ Body Plan MantleMantle

Thin layer of tissue that covers the body Thin layer of tissue that covers the body organsorgans

Mantle cavity (Mantle cavity (between soft body and mantlebetween soft body and mantle)) Contains the gills that are used to Contains the gills that are used to

breathe by exchanging oxygen and breathe by exchanging oxygen and carbon dioxide in the watercarbon dioxide in the water

Open Circulatory SystemOpen Circulatory System Most mollusk have thisMost mollusk have this Moves blood through vessels and into Moves blood through vessels and into

open spaces around body organsopen spaces around body organs