Invertebrates

Chapter 29 and 30Sponges, Cnidarians, Flatworms, Roundworms, mollusks, annelids

Animal Kingdom Characteristics

- multicellular- eukaryotic- heterotrophs- movement- tissues

Body Plans

- Bilateral Symmetry- equal halves in one direction

Radial Symmetry

• - 360 degrees; equal halves

- Asymmetry- cannot cut in equal halves

Body Development - Ectoderm- outside body layer- skin and hair- Endoderm- inside body layer- digestive tract

- Mesoderm-middle layer- muscles,

blood and organs

- Types of Body Cavities:

1. Coelom- true body cavity- surrounded by mesoderm

-2. Pseudocoelom- false cavity- between mesoderm and endoderm

3. Acoelomate

No body cavity.

Let’s Review.

What type of symmetry is this?

What type of symmetry?

Symmetry?

- Vertebrates- animals with backbones

- fish, amphibians, reptiles, birds, and mammals

- Invertebrates- animals without backbones

- sponges, cnidarians, mollusks, worms, echinoderms, arthropods

Sponges: Phylum PoriferaAsymmetrical – no symmetryNo tissues or organs (cells work together to perform a specific function2 body layers: endo-, ecto-Sessile – do not moveVariety of shapes and colorsAcoelemate – no body cavity

Variety of Sponges

                                       

Digestion of sponges

Sponges are consumersFeed on bacteria, algae, protozoans (filter feeders)

Sponge digestion continued:

Reproduction

Either sexual or asexualAsexual- fragmentation- each piece of sponge will grow into a complete new spongeSexual- hermaphrodite- produce both eggs and sperm- release into water at different times-sperm from one enters pores of other to fertilize eggs- External fertilization

Reproduction continued

Produces a zygote- free swimming larvae for a short time- attaches to surface- new sponge

Cnidarians- the stingersCoral

Characteristics of Cnidarians

Two Types: Polyp – sessile, tube-like

with tentacles ex. Coarl, sea anemone

Medusa – free swimming, umbrella shaped

Jellyfish

Has tissues – ecto-, endo-Nematocysts – stinging cells on tentaclesRadial symmetryacoelamate

B

How Cnidarians Get O2?

Diffusion

Have nervous tissue.

Reproduction

Asexual- budding- small extensions of body grow and then breaks away from parent

Sexual-some species are hermaphrodites Others, female releases egg and male releases

sperm into water- External fertilization

hydra

Portugese Man of War (colony)

Jelly fish

Sea anemone

Sea Anemones

Coral reef

Coral reefs

Structure See diagram – oldest

part is deeper. Newest is toward the top.

Live symbiotically with unicellular yellow brown algae- zooxanthellae

Benefit of Symbiotic Relationship:Coral gets:food

(coral can also capture food with tentacles)Algae gets:

Protection and access to sunlight

Coral Bleaching

When coral ejects it’s algae- coral turns whiteCoral doesn’t get enough food- dies

Coral bleaching due to:

DiseasesIncreased Ultra violet radiationSedimentationPollutionIncreased water temperaturesDirect destruction by humans- anchors, touching while diving

Bleached coral

Flatworms

AcoelomateBilateral symmetry

Platyhelminthes – flatworms

Characteristics of flatworms:

Can be parasitic, or free living 1 body openingHermaphrodites or asexual reproduction by regeneration: breaking in 2, and each becomes a new organism Get O2 through skin- diffusion

Tapeworm

Body Two parts: Scolex – head Proglottids – body

sectionsAttach to inside of intestinesParasiteEx. Beef tapeworm: become infected by eating raw beef.

Getting Beef tapeworm:

Blood fluke - causes Schitomiasis

Planeria

Eyespots- light Pharynx- extends like a straw, releases enzymes- breaks down food , sucks it upSensory pits on side of head, detect food, chemicals, and movement Ability to regenerate

planeria

29-4 Roundworms

PseudocoelumTube within a tube body2 body openingsMove in a side to side mannerparasites

Ex. Ascaris - hookworm

Carried through human waste to soilIf ingested eggs enter large intestine – becomes larvaeLarvae bore through blood vesselsBack to the intestine to mate

Ascaris in pig intestine

Trichinella – pork roundworm

Causes TrichinosisEating improperly cooked pork

                                                                                                                    

Lymphatic Filariasis

                                                                                  

Mollusks and Annelids

Chapter 30

Mollusks

Characteristics Invertebrates Larval stage Marine, freshwater,

terristrial coelomates

Mollusks have 3 parts to body:

Visceral mass – contains organsMantle – tissue around visceral mass (secretes a shell)Foot - locomotion

Other Mollusk characteristics:

Exoskeleton Sometimes called a

valveOuter skeleton

•Radula

(not in bivalves)Tongue-like structure

Organ systems of mollusks:

Excretory – get rid of waste:Open Circulatory System –heart pumps fluid through a series of vessels out into body cavity

Organ Systems of Mollusks

Reproduction – most have separate sexes, external fertilizationRespiration – use gills

30-2 Groups of Mollusks

Bivalves – “two valves”Valves held together by strong musclesNo radulaFilter feedersExamples: clams, oysters, scallops

Bivalve Photos

Gastropods

Examples are snails and slugsSingle shell or noneUse radula to scrape food off of rocks etcLand snails – hermaphrodites, aquatic snails – separate sexesHerbivoresGills or lungs?

Cephalopods – “head footed”

Examples: squid, octopusLarge head with tentaclesEyesMarine predators (consumers)Ink sac – for protectionInternal shell – penBrain present – complexSkin can change colorgills

Phylum Annelida

Segmented wormsExamples: earthworms, leeches, sandwormsSegmented bodyCoelum Bilateral symmetryAbundant in all habitats

Organ Systems in Segmented Worms

Closed circulatory systemExcretory system – nephridiaBreath through skinBristles – setaeReproduction – hermaphrodites

Digestion of Earthworm

Pathway of food: Pharynx – soil enters Esophagus - Crop-storage Gizzard- muscular for

grinding soil Intestines – absorption anus

Groups of Annelids

Marine segmented worms

Leeches