1. Mollusks, Arthropods, Echinoderms

2. Mollusks Soft-bodied invertebrates Have bilateral symmetry
Usually have one or two shells with organs in a fluid filled cavity
Most live in water
Many different species

3. Mollusks’ Body Plan Mantle
Thin layer of tissue that covers the body organs
Mantle cavity (between soft body and mantle)
Contains the gills that are used to breathe by exchanging oxygen and carbon dioxide in the water
Open Circulatory System
Most mollusk have this
Moves blood through vessels and into open spaces around body organs

4. Mollusks’ Body Plan
Have a well developed head with a mouth and some sensory organs
Underside is a muscular foot
Moves by making rhythmic contractions

5. Classification of Mollusks
Classified into three common groups based on shell presence, type and foot type
Gastropods
Bivalves
Cephalopods

6. Gastropods Largest group of mollusks Usually have a single shell
Use a radula (a tongue-like organ with rows of teeth) to get food
Have foot glands that secrete a layer of mucus for sliding
Includes snails, conchs, and garden slugs

7. The Radula

8. Obtaining Food
Some gastropods are herbivores. These include animals that eat only plants.
Other gastropods are carnivores. These include animals that eat only other animals.

9. Bivalves Have a hinged, two-part shell
To open or close their shell they either contract or relax their muscles
Includes clams, oysters, scallops, & mussels
Well adapted for water
Clams can burrow in sand
Mussels attach themselves to a solid surface
Scallops escape predators by rapidly opening and closing their shell

10. Pearls

11. Cephalopods Most specialized and complex mollusks.
Include squid, octopuses, and chambered nautiluses.
Have a well developed head and many tentacles for capturing prey.
Closed circulatory system
Moves blood through the body in a series of closed vessels like humans.
Use jet propulsion to move at speeds of 6 m/s.

12. Origin of Mollusks
Mollusk fossils date to more than 500 million years ago
Some species of mollusk, like the chambered nautilus, have changed very little from their ancestors
Today’s mollusks are descendants of ancient mollusks

13. Value of Mollusks Provide food for people and other animals
Many people make their living raising or collecting mollusks to sell
Shells can be used for jewelry and decoration
Pearls are produced by several species of mollusks most are made by pearl oysters

14. Negative Effects of Mollusks
Land slugs and snails can damage plants
Certain species of snails are hosts for parasites that can infect humans
Bacteria and viruses can become trapped in these animals because they are filter feeders…thus eating them could result in sickness or even death!

15. Arthropods Characteristics
Largest group of animals (over 1 million species)
Have jointed appendages which include legs, antennae, claws and pincers (Chelipeds)
Have bilateral symmetry, segmented bodies, exoskeletons, a body cavity, a digestive system with two openings and a nervous system
Most have separate sexes and reproduce sexually
Adapted to live in almost every environment and range in size from dust mite to Japanese spider crabs

16. Origin of Arthropods Some fossils are more than 500 million years old
Scientist hypothesized that arthropods probably evolved from an ancestor of segmented worms because they have body segments
The hard exoskeleton and walking legs allowed arthropods to be among the first animals to live successfully on land

17. Value of Arthropods A source of food
Agriculture would be impossible without bees and other insects to pollinate crops
Useful chemicals are obtain from some arthropods
Important part of ecological community

18. Arthropods Body Segments
Bodies of these animals are divided into segments similar to segmented worms
Some have many segments, others have segments that are fused together to form body regions
Exoskeleton
A hard outer covering that supports and protects the internal body and provides places for muscle to attach.
Doesn’t grow as the animals does, it is shed and replaced during a process called molting
While the animal are molting they are very vulnerable to predators because they have a soft out covering until the new exoskeleton hardens. Before the exoskeleton hardens the animal makes itself larger by taking in air or water so that there is room to grow into the exoskeleton

19. Crustaceans
Have jointed appendages which include legs, one or two pairs of antennae, claws and pincers (Chelipeds) which are used for crushing food.
Most live in water, but some live in moist environments on land—such as pill bug.
Have five pair of legs, first pair of legs are claws for catching and holding food.

20. Crustaceans
Swimmerets are appendages on the abdomen which help in movement and are used in reproduction; also force water over the gills used in O2 and CO2 exchange
If a crustacean loses an appendage it can regenerate it!

21. Crayfish Anatomy

22. Arachnids Have two body sections, four pairs of legs, and no antennae.
Scorpions
Have sharp, poison filled stinger at the end of abdomen.
Have a well-developed appendages which they can grab their prey.
Spiders
Can’t chew their food, release enzymes into prey to digest it—then suck the predigest liquid into its mouth.
Have book lungs where O2 and CO2 are exchanged.

23. Arachnids Mites & Ticks Most are parasites
Ticks have specialized mouthparts to remove blood from the host.
Ticks often carry disease such as Lyme Disease.

24. Centipedes & Millipedes
Have long bodies and many segments, exoskeleton, jointed legs, antennae and simple eyes.
Found in damp environments
Reproduce sexually
Make nests for eggs and stay with them until they hatch.
Centipedes are predators
Millipedes feed on decaying plant matter.
Centipedes have one pair of legs per segment
Millipedes have two pair of legs per segment

27. Insects Have three body regions Head Thorax Abdomen
Has a pair of antennae, eyes and a mouth
Thorax
Three pairs of legs and one or two pairs of wings if present are attached here
Abdomen
Where reproductive structures are found

28. Insect Anatomy

29. Insects
Have an open circulatory system that carries digestive food to cells and removes wastes
Insect blood doesn’t carry O2 instead air enters and exits through openings called spiracles found on the abdomen and thorax
Are the only invertebrate animals that can fly

30. Insects & Food
Feed on a number of things have different mouth parts to obtain food
Grasshoppers and ants have large mandibles for chewing
Butterflies and honey bees have siphons for lapping up nectar
Aphids and mosquitoes have mouth parts that are adapted for piercing into plants or other organisms
Centipedes and praying mantises eat other animals, some moths eat wool clothing

31. Metamorphosis A series of changes that an insect goes through
Two types
Complete
Includes stages of egg, larva, pupa, and adult
Ex. Butterflies, bees, flies
Incomplete
Includes stages of egg, nymph, adult
The nymph form molts several times before becoming an adult
Ex. Grasshoppers, crickets

32. Complete Metamorphosis

33. Gradual Metamorphosis

34. Insects success Insects are extremely successful based these reasons
Tough flexible, waterproof exoskeleton
Ability to fly
Rapid reproduction cycles
Small sizes
Some insects have other adaptations that allow them to be successful
Camouflage/mimicry.

35. Controlling Insects
Not all arthropods are of value some are pests that carry disease or can damage crops
Another negative for using insecticides is that some toxins stay in the environment and can accumulate in other organisms that eat those insects which in turn can be eaten by larger organisms causing illness or death

36. Controlling Insects Common ways to control insects
Insecticides, but these also kill non-harmful insects
Biological controls
Types of bacteria, fungi, and viruses can be used to control insects
Natural predators being released to kill the harmful insect
Some how interfere with reproduction of the particular insect

37. Echinoderms Characteristics
Have an endoskeleton covered by a thin, bumpy or spiny epidermis
Radial symmetrical—allowing them to sense food, predators and other things in the environment from all directions
Have mouth, stomach, intestines
Feed on a variety of plants and animals
Have no head or brain, but have a nerve ring that surrounds the mouth
Also have cells that respond to light and touch

38. Water-Vascular System
A characteristic unique to echinoderms
Allows them to move, exchange CO2 and O2, capture food, and release wastes
It is a network of water-filled canals with thousands of tube feet connected to it.
Tube feet—hollow, thin walled tubes that ends in a suction cup.
As pressure in the tube feet changes the animal is able to move along by pushing out and pulling in its tube feet

39. Characteristics of Echinoderms
Echinoderms, such as this sea star, have a water vascular system that helps them move and catch food.

40. Types of Echinoderms Sea Stars
Echinoderms with at least 5 arms arranged around a central point
Uses tube feet to open shells of prey, once open pushes its stomach into shell and uses an enzyme to digest it
Reproduce sexually
Can repair themselves by regeneration

42. Types of Echinoderms Brittle Stars
Have fragile, slender, branched arms that break off easily
This adaptation allows them to survive
They can regenerate broken off body parts
Use flexible arms for movement and tube feet to get food into their mouths
While the predator is eating the broken off arm the remaining part of the animal can escape

43. Types of Echinoderms Sea Urchins & Sand Dollars
Disk or globe-shaped animals covered in spines
Spines help in movement and in burrowing
Also can protect them from predators
Sea Urchins have five tooth like structures around their mouth

44. Types of Echinoderms Sea Cucumber Soft bodied echinoderms
Have a leathery covering
Have tentacles around their mouth and rows of tube feet on their upper and lower surfaces
When threatened, they may expel their internal organs which will then be regenerated in a few weeks.

45. Value of Echinoderms Feed on dead organisms in the marine environment
Help recycle material
Used for food
Possible sources of medicine
Sea stars can help control the population of other organisms

46. Origin of Echinoderms Date back more than 400 million years ago
Earliest echinoderms had bilateral symmetry as adults
Scientists hypothesize that echinoderms more closely resemble animals with backbones than any other group of invertebrates
Have similar embryos that develop similar to vertebrates
Complex body systems