Presentation on theme: "The Animal Clade Extant"— Presentation transcript:
1The Animal Clade Extant PlatyhelminthesacoelomatesArthropodaAnnelidaMolluscaprotostomiaNematodaRotiferapseudo-coelomatesHemichordataEchinodermataPoriferaparazoaCnidariaChordatadeuterostomiacoelomatesradiataThis cladogram omits several smaller animal phyla!bilateriaeumetazoa (true tissues)loss of chloroplast, colonial organizationAncestral Choanoflagellate
2Domain Eukarya Kingdom Animalia Phylum Mollusca AnimalsDomain EukaryaKingdom AnimaliaPhylum Mollusca35,000 species making this the second-largest phylum of Animalia
3Polyplacophora: chitons The most-primitive mollusc has 8 valves (plates) protecting its soft tissues beneath. The chiton foot attaches to rocks and the animal uses its radula to scrape organic material from the rock surfaces.
4After working hard to remove the “suck rock” organism from the rock, the ventral surface of the chiton shows the obvious mollusc features.gillsfootmouth(radula inside)
5The chiton has multiple eyes. Some are just light-sensitive spots. The primary eyes are of a lens-type. Many chiton species lack eyes.
6This cartoon shows a longitudinal slice of a chiton with the three principal parts: foot (locomotion or attachment), visceral mass (internal organs), and mantle (secretes valves).dorsal aortagonadheartvalve platespericardial cavity(coelom)hemocoelventricleradulaauriclemantlemouthanusfootdigestive glandstomachnephridiumnephridioporeventral nerve cord(not shown)gonopore
7As for all other molluscs, chitons use a radula to scrape their food from environmental surfaces. Below is a radula removed from a chiton mouth.
8Gastropoda: snails and relatives (slugs) Snails have a single spiral-shaped valve (univalve)Slugs and nudibranchs have lost this feature.shelloptical tentacleeyefootgonoporesensory tentacles
9And now for a look inside our gastropod mollusc… Trochophore larva:And now for a look inside our gastropod mollusc…Veliger larva:The shell obviously provides a hard covering for the visceral mass.The snail shown here is a pulmonate, with a vascularized mantle cavity serving as a lung. Vascularizing this led to loss of the gills in most gastropods.The gastropods, are clearly hermaphroditic, and some are self-fertile.
10This is a slug, its mantle is reduced to a “saddle” and does not secrete a shell. The other features of the snail are all present.optical tentaclessensory tentaclesmantlefootskirt
11Here is the longitudinal section of an optical tentacle. The eye of the slug is a lens-type eye.1. digitate ganglion2. collar cell3. olfactory nerve4. tentacle retractor muscle5. lateral processed cell6. lateral oval cell7. optic nerve8. accessory retina9. lens10. retinaretinal cell:11. microvilli12. pigment cell13. light sensitive cell
12Here is a micrograph of a longitudinal section of a snail eye The tentacle has all of the optical, sensory, and neural parts we expect for vision.The tentacle has all of the sensory, and neural parts we expect for chemical sensation too.The sensory tentacles have these features too.olfactoryganglionnervelensretinaopticnerve
13The slug shows the pneumostome in the mantle for breathing. footmantleoptical tentaclesskirtsensory tentacles
14These two slugs are showing mating behavior. The slugs are dangling on a slime thread and grip each other with their feet.The slugs evert their reproductive organs out through the gonopore.The organs unite and spermatophores are exchanged.Sperm are stored in a spermatheca for a week or more. Syngamy and deposition of zygotes occurs later.
15This group includes the clams, oysters, mussels, and scallops. Bivalva: bivalvesThis group includes the clams, oysters, mussels, and scallops.Their body is typical mollusc too, but with two hinged valves (shells)graphics/jpegs/aopercu.jpg
16Adductor muscles to hold the valves together. Here is a cartoon of a lateral view of the foot, visceral mass and mantleAdductor muscles to hold the valves together.Bivalves have gills rather than lungs.Their incurrent siphons take in plankton lodging in mucus.The mucus laden particles gather on the gills (palps) and enter the mouth.The mouth lacks the radula.
17The foot can push a bivalve through sediments. This cartoon is shows a plane of section perpendiular to the previous one.hinge and ligamentThe foot can push a bivalve through sediments.The food-trapping gills are used for gas exchange.The heart pumps the blood into the hemocoel bathing the tissues. It goes through the gills for gas exchange. The blood then returns to the heart.shellheartnephridiumintestinemantlegonadgillsfootNephridia cleanse the blood of nitrogenous waste.
18Here are three different molluscs Here are three different molluscs. Between the valves of the bivales the mantle fringe is quite visible. With the valves ajar, the bivalve can carry out its filter feeding. If you swim nearby, the bivalve adductor muscles snap the valves shut.
19How does the bivalve know you are swimming by? Eyes!
20Here are close-ups of the bivalve eye and a cartoon of its structure. This gives the impression of being somewhat intermediate between a lens-type and a pinhole-type eye.
22Cephalopoda: the chambered nautilus, squid, and octopus The nautilus has gastropod featuresoperculumeyevalvetentacles
23Advantage: simple, detailed Disadvantage: low light collectionPinhole eye of Nautilusretinapinhole
24Smaller arms surround the mouth This Caribbean reef squid is small. The giant squid is the largest invertebrate animal known…17 meters long…2 tons!finmantlechromatophoreseyeSmaller arms surround the mouthTwo grasping tentacles
25Between the tentacles part of the beak is shown. Contrary to the filename, this is a Humboldt squid. It is certainly large, but is not the giant squid.Between the tentacles part of the beak is shown.The eyes face the man’s knee and elbow.The mantle is in his lap and the fin is over his shoulder.
26The squid eye is a lens-based eye, rather than a pinhole eye. The squid eye is a lens-based eye, rather than a pinhole eye.Is this cartoon correct, based upon your dissection of the squid in class?retinalensAdvantage: collects more light
27Another cephalopod is the octopus. It obviously has eight tentacles surrounding the mouth…no, duh!This one is obviously swimming.
28Here is another swimming octopus Here is another swimming octopus. The idea of cephalopod (head-foot) is shown nicely here. Behind one tentacle the siphon is showing the basis for jet-action locomotion among cephalopods.
29What kind of eye does an octopus have? What kind of eye does an octopus have?Squid eyeNote: I am fairly certain that the animal shown above on the right is a squid, rather than an octopus: