1. 4. Bilaterally Symmetrical Worms

2. Marine worms, and organisms hereafter, kick it up a notch exhibiting bilateral symmetry (just like humans).Marine worms, and organisms hereafter, kick it up a notch exhibiting bilateral symmetry (just like humans). Instead of addressing front and back, we will discuss anterior, posterior, dorsal and ventral.Instead of addressing front and back, we will discuss anterior, posterior, dorsal and ventral. Also pick up a CNS!Also pick up a CNS! Bilateral symmetry, and all that goes with it, results in enhanced motion and sophisticated behaviors.Bilateral symmetry, and all that goes with it, results in enhanced motion and sophisticated behaviors.

3. 4. Bilaterally Symmetrical Worms Anterior – head with brain or accumulation of nerve cells and sensory organs like eyesAnterior – head with brain or accumulation of nerve cells and sensory organs like eyes Posterior – bottom/backsidePosterior – bottom/backside Dorsal – backDorsal – back Ventral – BellyVentral – Belly Bilateral symmetry allows organisms to actively pursue prey and develop sophisticated behaviorsBilateral symmetry allows organisms to actively pursue prey and develop sophisticated behaviors

4. A. Flatworms: Phylum Platyhelminthes A. Flatworms: Phylum Platyhelminthes Simplest flatworms – has CNSSimplest flatworms – has CNS Simple brain – aggregation of nerve cellsSimple brain – aggregation of nerve cells Several nerve cord running from brain through length of bodySeveral nerve cord running from brain through length of body Nervous system coordinates movement of well-developed muscular system.Nervous system coordinates movement of well-developed muscular system.

5. A. Flatworms: Phylum Platyhelminthes A. Flatworms: Phylum Platyhelminthes Gut has an openingGut has an opening Have a middle layer of tissues, in developing embryos it is called mesodermHave a middle layer of tissues, in developing embryos it is called mesoderm Mesoderm gives rise to muscles, reproductive system and other organsMesoderm gives rise to muscles, reproductive system and other organs 20,000 known species20,000 known species Turbellarians are the most common – striking color patternsTurbellarians are the most common – striking color patterns Live in or on oysters, crabs, and other invertebratesLive in or on oysters, crabs, and other invertebrates

6. A. Flatworms: Phylum Platyhelminthes A. Flatworms: Phylum Platyhelminthes Flukes (trematodes) Largest group (6,000 species) Largest group (6,000 species) All parasitic All parasitic Feed on tissues, blood, or intestinal contents Feed on tissues, blood, or intestinal contents Adult flukes live in vertebrates Adult flukes live in vertebrates Larvae may inhabit invertebrates like snails and clams or vertebrates like fish Larvae may inhabit invertebrates like snails and clams or vertebrates like fish Larva must be eaten by a vertebrate Larva must be eaten by a vertebrate Common in fish, seabirds, and whales Common in fish, seabirds, and whales

8. A. Flatworms: Phylum Platyhelminthes A. Flatworms: Phylum Platyhelminthes Tapeworms (cestodes) Parasitic Parasitic Have long body with repeating units Have long body with repeating units Head attaches to walls of gut by suckers and hooks Head attaches to walls of gut by suckers and hooks Lack gut or mouth Lack gut or mouth Absorb nutrients from host across body wall Absorb nutrients from host across body wall Found in invertebrates and vertebrates Found in invertebrates and vertebrates Longest recorded in sperm whale was 50 feet!! Longest recorded in sperm whale was 50 feet!!

9. B. Ribbon Worms: Phylum Nemertea B. Ribbon Worms: Phylum Nemertea More complex than flatwormsMore complex than flatworms Complete digestive tract (mouth, gut, anus)Complete digestive tract (mouth, gut, anus) Have a circulatory systemHave a circulatory system Proboscis – long flesh tube to capture preyProboscis – long flesh tube to capture prey Everted in cavity above mouthEverted in cavity above mouth Feed on worms and crustaceansFeed on worms and crustaceans 900 species, mostly marine900 species, mostly marine Found in all oceans, most common in shallow temperate watersFound in all oceans, most common in shallow temperate waters

10. B. Ribbon Worms: Phylum Nemertea B. Ribbon Worms: Phylum Nemertea Some nocturnal, some brightly colored found under rocks at low tidesSome nocturnal, some brightly colored found under rocks at low tides Elastic, and proboscis may extend to a meter or more beyond body lengthElastic, and proboscis may extend to a meter or more beyond body length Longest invertebrate – reaches 100 ft!!Longest invertebrate – reaches 100 ft!!

11. C. Nematodes: Phylum Nematoda Roundworm numbers are staggering in the marine world, yet hardly ever seenRoundworm numbers are staggering in the marine world, yet hardly ever seen Many are parasitic and found in most marine organisms.Many are parasitic and found in most marine organisms. Adapted to live in sediment or tissues of other organismsAdapted to live in sediment or tissues of other organisms

12. C. Nematodes: Phylum Nematoda Typically pointed at both endsTypically pointed at both ends Anus lies within body cavity filled with fluid that transports nutrientsAnus lies within body cavity filled with fluid that transports nutrients Layer of muscle in the tough but flexible body pushes and squeezes against the fluid which acts as hydrostatic skeleton that provides support and aids in locomotionLayer of muscle in the tough but flexible body pushes and squeezes against the fluid which acts as hydrostatic skeleton that provides support and aids in locomotion

13. C. Nematodes: Phylum Nematoda 10,000 to 25,000 species and estimates that half a million still undiscovered10,000 to 25,000 species and estimates that half a million still undiscovered Anisakis and few related inhabit seals and dolphinsAnisakis and few related inhabit seals and dolphins –Larvae found on flesh of many types of fish and may infect humans who eat raw or poorly cooked fish –Often larvae are vomited or coughed up without further complications – Sometimes penetrate into walls of stomach or intestine causing symptoms similar to ulcers

14. D. Segmented Worms (phylum Annelida) 20,000 spp. known as Annelids20,000 spp. known as Annelids First example of segmentation.First example of segmentation. Gut through all segments and lies in cavity known as coelomGut through all segments and lies in cavity known as coelom –Coelom fluid filled and divided by partitions

15. D. Segmented Worms (phylum Annelida) Segments acts as hydrostatic skeleton contracting in sequence by muscles in bodySegments acts as hydrostatic skeleton contracting in sequence by muscles in body Efficient crawlers and burrowersEfficient crawlers and burrowers

17. i. Polychaetes (class Polychaeta) i. Polychaetes (class Polychaeta) Body segments of most have a pair of flattened extensions or parapodiaBody segments of most have a pair of flattened extensions or parapodia Parapodia have stiff sharp bristles (setae)Parapodia have stiff sharp bristles (setae) Have closed circulatory systemHave closed circulatory system Muscular contractions help circulation of bloodMuscular contractions help circulation of blood In small organisms, oxygen in water can easily move across body wall to all tissuesIn small organisms, oxygen in water can easily move across body wall to all tissues Large organisms have gills on parapodiaLarge organisms have gills on parapodia Parapodia -Parapodia - One of the fleshy paired appendages that function in locomotion and breathing Gills - thin wall extensions of body that have capillaries where gas exchange takes placeGills - thin wall extensions of body that have capillaries where gas exchange takes place

18. Sandworm Nereis

19. i. Polychaetes (class Polychaeta) Have planktonic larval stage – trochophoreHave planktonic larval stage – trochophore Biologists compare larvae stage of polychaetes with other invertebrates to examine evolutionary relationshipsBiologists compare larvae stage of polychaetes with other invertebrates to examine evolutionary relationships Body 5-10cmBody 5-10cm Many crawl and hide under rocksMany crawl and hide under rocks Have several pairs of eyes and other sensory organsHave several pairs of eyes and other sensory organs Use proboscis with jaws to capture preyUse proboscis with jaws to capture prey Others are deposit feederOthers are deposit feeder

20. i. Polychaetes (class Polychaeta) i. Polychaetes (class Polychaeta) Many live in temporary or permanent tubes made from mucus, proteins, bits of seaweed, cemented mud particles, sand grains, or tiny fragments of shellsMany live in temporary or permanent tubes made from mucus, proteins, bits of seaweed, cemented mud particles, sand grains, or tiny fragments of shells Tube dwelling have reduced parapodiaTube dwelling have reduced parapodia Have tentacles which have cilia and mucus that catch organic particles and move them to their mouthsHave tentacles which have cilia and mucus that catch organic particles and move them to their mouths Some use feathery tentacles covered with cilia to capture, sort, and transport particlesSome use feathery tentacles covered with cilia to capture, sort, and transport particles Some of calcium carbonate tubes built on rocks and other surfacesSome of calcium carbonate tubes built on rocks and other surfaces

21. This feather-duster worm, Sabella melanostigma, is a perfect example of beauty, form and function.

22. i. Polychaetes (class Polychaeta) i. Polychaetes (class Polychaeta) Some are ptanktonic and use flat parapodia to swimSome are ptanktonic and use flat parapodia to swim The Palolo worm break off & posterior half swims up to surface to spawnThe Palolo worm break off & posterior half swims up to surface to spawn Timed with phases of the moonTimed with phases of the moon Some places people with gather worms for foodSome places people with gather worms for food Live on external surface of sea stars & sea urchins, in burrows of invertebrates, and shells of hermit crabsLive on external surface of sea stars & sea urchins, in burrows of invertebrates, and shells of hermit crabs

23. Beard worms (pogonophorans) Highly specialized lack gut and mouthHighly specialized lack gut and mouth Tuft (thousands of long tentacles) absorb nutrients in dissolved waterTuft (thousands of long tentacles) absorb nutrients in dissolved water Some have symbiotic relationship w/ bacteriaSome have symbiotic relationship w/ bacteria Bacteria use the nutrients to manufacture food for the wormBacteria use the nutrients to manufacture food for the worm Mostly restricted to deep waterMostly restricted to deep water 4-7 feet4-7 feet Related vestimentiferans grow larger and found at hydrothermal ventsRelated vestimentiferans grow larger and found at hydrothermal vents

25. ii. Oligochaetes (subclass Oligochaeta) ii. Oligochaetes (subclass Oligochaeta) Small and found in mud and sand feeding on detritusSmall and found in mud and sand feeding on detritus Lack parapodiaLack parapodia

26. iv. Leeches (class Hirudinea) Blood sucking found attached to fish and other invertebratesBlood sucking found attached to fish and other invertebrates Distinguished by suckers and no parapodiaDistinguished by suckers and no parapodia

27. E. Peanut Worms (phylum Sipuncula) E. Peanut Worms (phylum Sipuncula) Soft unsegmented bodiesSoft unsegmented bodies Burrow in muddy bottoms, rocks, corals, and empty shellsBurrow in muddy bottoms, rocks, corals, and empty shells All are marine living in shallow watersAll are marine living in shallow waters Deposit feedersDeposit feeders Long anterior portion of body contains mouth and set of small lobes or branching tentaclesLong anterior portion of body contains mouth and set of small lobes or branching tentacles Tentacles can be pulled into remaining body, become compactTentacles can be pulled into remaining body, become compact 1-35 cm in length1-35 cm in length

28. F. Echiurans (phylum Echiura) F. Echiurans (phylum Echiura) Soft segmented sausages buried in mud or in coralSoft segmented sausages buried in mud or in coral Look like peanut w/out retractable spoon-like or forked proboscisLook like peanut w/out retractable spoon-like or forked proboscis Deposit feeders that use proboscis to gather organic matterDeposit feeders that use proboscis to gather organic matter Urechis caupo lives in U-shaped tubes in mudUrechis caupo lives in U-shaped tubes in mud