Mollusks, Mollusks, Echinoderms, Echinoderms, and Arthropodsand Arthropods

Biology 11Biology 11

Phylum Mollusca Phylum Mollusca pgs 428-432pgs 428-432

Examples: snails, clams, oysters, squidExamples: snails, clams, oysters, squid

Habitat: mostly aquatic and terrestrial Habitat: mostly aquatic and terrestrial 7 classes: Gastropods, Pelecypod, 7 classes: Gastropods, Pelecypod,

Cephalopods, Polyplacophora, Cephalopods, Polyplacophora, Scaphopod, Aplacophora, Scaphopod, Aplacophora, MonoplacophoraMonoplacophora

Body plan DevelopmentBody plan Development Bilateral SymmetryBilateral Symmetry Three germ layersThree germ layers True coelomTrue coelom Protosomes pg 428Protosomes pg 428 Basic body plan includes:Basic body plan includes:

Foot – for locomotionFoot – for locomotion Mantle – hanging tissueMantle – hanging tissue Shell – internal or external, calcium Shell – internal or external, calcium

carbonatecarbonate Gills – respiratory structures (aquatic)Gills – respiratory structures (aquatic) Visceral mass – internal organsVisceral mass – internal organs

Mollusks SystemsMollusks Systems Sexual Reproduction – Hermaphroditic with Sexual Reproduction – Hermaphroditic with

cross fertilization, or separate sexes.cross fertilization, or separate sexes.

Circulatory System - Closed Circulatory Circulatory System - Closed Circulatory SystemSystem

Digestion – Radula (a rough tongue) and Digestion – Radula (a rough tongue) and filter feeding. A complete digestive tract.filter feeding. A complete digestive tract.

Nervous System – Primitive brain and light Nervous System – Primitive brain and light receptors or eyes.receptors or eyes.

Respiration – Gills are covered by the mantle.Respiration – Gills are covered by the mantle.

Phylum Echinodermata Phylum Echinodermata pgs 432-434pgs 432-434

Echinos =spiny or bristlyEchinos =spiny or bristly Derm= skinDerm= skin Examples:Examples: Starfish, sea urchin, sand Starfish, sea urchin, sand

dollar, sea cucumberdollar, sea cucumber

Habitat – aquatic actually means Habitat – aquatic actually means fresh water so they actually live in fresh water so they actually live in MARINE environments. MARINE environments.

Water Vascular systemWater Vascular system

The major unifying characteristic of The major unifying characteristic of echinoderms is their water vascular echinoderms is their water vascular system. system.

Locomotion and feeding are Locomotion and feeding are accomplished by this system, which accomplished by this system, which operates much like a hydralic pump.operates much like a hydralic pump.

EchinodermEchinoderm

Echinoderms are the closest relatives to Echinoderms are the closest relatives to Chordates. It may not seem so at first, but Chordates. It may not seem so at first, but looking closely at embryological evidence, looking closely at embryological evidence, it is believed that chordates and it is believed that chordates and echinoderms shared a common relative. echinoderms shared a common relative. This relative is believed to have been This relative is believed to have been something along the lines of sea urchin - something along the lines of sea urchin - an orgasnism a bit larger than a golf ball an orgasnism a bit larger than a golf ball with spines extending radially. Interesting with spines extending radially. Interesting little creatures, they aren't especially little creatures, they aren't especially intelligent. In fact, they don't do much of intelligent. In fact, they don't do much of anything.anything.

Keep in mind that "close" is a Keep in mind that "close" is a relative term. New York and Sydney relative term. New York and Sydney are close compared to the distance are close compared to the distance between the earth and Jupiter. It is between the earth and Jupiter. It is all a matter of context. In evolution, all a matter of context. In evolution, the context is a matter of many the context is a matter of many millions of years.millions of years.

Body plan DevelopmentBody plan Development Bilateral Symmetry in larvae, Bilateral Symmetry in larvae, Radial Symmetry in adults (Radial Symmetry in adults (Secondarily Secondarily

derived pentaradial symmetry. What does derived pentaradial symmetry. What does that mean? It means that echinoderms tend to that mean? It means that echinoderms tend to be pentaradially symmetric. The secondarily be pentaradially symmetric. The secondarily derived portion of that means that they switch derived portion of that means that they switch from being bilaterally symmetric to radially from being bilaterally symmetric to radially symmetric as they mature. This is of no symmetric as they mature. This is of no consequence to taxonomists, they use the consequence to taxonomists, they use the symmetry at the larval stage. symmetry at the larval stage.

Three germ layersThree germ layers True coelomTrue coelom Deuterosomes pg. 432Deuterosomes pg. 432

Echinoderm SystemsEchinoderm Systems Water vascular system – unifying systems between all Water vascular system – unifying systems between all

echinoderms. Allows for some locomotion.echinoderms. Allows for some locomotion.

Circulatory System – open circulatory systemCirculatory System – open circulatory system

Digestion – one way digestive tube. Filter feeding and Digestion – one way digestive tube. Filter feeding and ingestion through the mouth.ingestion through the mouth.

Nervous System – oral and radial nerve cords but NO Nervous System – oral and radial nerve cords but NO Brain.Brain.

Respiration – diffusionRespiration – diffusion Reproduction- Reproduction- Echinoderms are Echinoderms are monoeciousmonoecious, that means , that means

that the sexes are separate. Males are males, females are that the sexes are separate. Males are males, females are females. There is no ambiguity. However, with females. There is no ambiguity. However, with echinoderms, the sexes are not readily apparent using the echinoderms, the sexes are not readily apparent using the unaided eye. unaided eye.

Phylum Arthropoda Phylum Arthropoda Pgs Pgs 435-441435-441

Arthropoda = jointed appendagesArthropoda = jointed appendages Examples: insects, crayfish, spidersExamples: insects, crayfish, spiders

Habitat: ubiquitous (almost Habitat: ubiquitous (almost everywhere!)everywhere!)

Largest animal phylaLargest animal phyla 4 subphyla:4 subphyla:

Trilobitomorpha, Chelicerata, Uniramia, Trilobitomorpha, Chelicerata, Uniramia, Crustacea, Crustacea,

Body Plan developmentBody Plan development

Bilateral SymmetryBilateral Symmetry Three germ layersThree germ layers True coelomTrue coelom Various stages of metamorphosisVarious stages of metamorphosis Segemented bodies, all include a head, Segemented bodies, all include a head,

thorax, abdomen and a chitin thorax, abdomen and a chitin exoskeleton.exoskeleton.

Developed nervous systems, compound Developed nervous systems, compound eyes or photoreceptors etc.eyes or photoreceptors etc.

Arthropod SystemsArthropod Systems Sexual reproduction – separate sexesSexual reproduction – separate sexes

Circulatory System – Open circulatory systemCirculatory System – Open circulatory system

Digestion – one way digestive tube, consisting Digestion – one way digestive tube, consisting or a foregut, midgut and hind gut. Pg 438or a foregut, midgut and hind gut. Pg 438

Nervous System – true brain with two ventral Nervous System – true brain with two ventral cordscords

Respiration – tracheal system and gillsRespiration – tracheal system and gills

Application Questions Application Questions (to be completed for homework)(to be completed for homework)

Read Pgs 428-434 and do practice Read Pgs 428-434 and do practice questions on Pg 434, Questions #2, questions on Pg 434, Questions #2, 3, 4, 7, 83, 4, 7, 8

Read Pgs 435-442 and do practice Read Pgs 435-442 and do practice questions on Pg 440, Questions #1, questions on Pg 440, Questions #1, 2, 3, 4 and 2, 3, 4 and Pg 442Pg 442 Question #5 Question #5