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On Cephalopods

On Cephalopods. By Claire and Asparaguy. What is a cephalopod?. 1: Pfeffer’s Flamboyant Cuttlefish ( Metasepia pfefferi ) 2: Bigfin Reef Squid ( Sepioteuthis lessoniana ) 3: Greater Blue-Ringed Octopus ( Hapalochlaena lunulata )

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On Cephalopods

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  1. On Cephalopods By Claire and Asparaguy

  2. What is a cephalopod? 1: Pfeffer’s Flamboyant Cuttlefish (Metasepia pfefferi) 2: Bigfin Reef Squid (Sepioteuthis lessoniana) 3: Greater Blue-Ringed Octopus (Hapalochlaena lunulata) 4: Shells of various species of nautiloids (Nautilus macromphalus, Allonautilus scrobiculatus, and Nautilus pompilius) 5: The Dumbo Octopus, Grimpoteuthis. 1 2 3 4 5 Can you identify these cephalopods? :D

  3. Overview of the cephalopods • A cephalopod is a member of the class Cephalopoda (phylum Mollusca) • Bilateral body symmetry • Prominent head • Set of tentacles or arms (number and type varies) • Ability to squirt ink • Cephalopod is Greek for “head-footed” • Two subclasses (Coleoidea and Nautiloidea)

  4. Overview of the cephalopods • The most intelligent invertebrates • Most have well-developed eyes • All cephalopods are active predators • Move by jet-propulsion – expelling water at high speed through a hyponome. • Most possess an ink sac which produces brown or purplish ink that is used to ward off attackers.

  5. Septum Umbilicus Camerae Simplified evolution of the extant cephalopods! Hyponome Image from Clarkson Tentacle Stomach Caecum Heart Tentacles Shell Gills Siphuncle Arms Beak Hyponome Digestive tract Gills Internalised shell Mantle

  6. Overview of the cephalopods • The ink of cephalopods: • When combined with less mucus, simply acts as a smokescreen to interfere visually with the predator • The ink’s tyrosinase may also irritate or inactivate the chemosensory systems of the predator. • When combined with large amounts of mucus, it forms a pseudomorph.

  7. Overview of the cephalopods • The beak of cephalopods: • Chitinous structures shaped like a parrot’s beak • Formed by the gradual hardening of tissues • Muscle around the beak is known as the buccal mass; also contains radula (a rough tongue)

  8. Overview of the cephalopods • Shells of the cephalopods: • Nautiluses retain an aragonitic external shell. • Squids have the squid pen or gladius. • Cuttlefish have a porous, aragonitic cuttlebone. • The shell is completely absent in most octopuses.

  9. Overview of the cephalopods • Cephalopod locomotion: • Squids move by drawing water into their mantle cavities and expelling it through their funnels. • Octopuses use the suckers on their arms to move about on the seafloor. • Cuttlefish undulates the fin fringe running along their mantles in addition to jet-propulsion (gas filled cuttlebone provides buoyancy) • Some squids, such as Ommastrephes bartramii, the neon flying squid, can “fly”!

  10. Overview of the cephalopods • Cephalopod locomotion: • The mantle is made of longitudinal and circular muscle fibres. • The circular muscles relax, expanding the mantle cavity. • The circular muscles then contract, sealing the opening. • The longitudinal muscles contract and expel the water. • http://www.biology.ualberta.ca/courses.hp/zool250/animations/Squid.swf

  11. Overview of the cephalopods • Squids such as the neon flying squid, or even the “jumbo” squid (Humboldt squid) can propel themselves out of the water and stabilise their flight with their fins.

  12. The cephalopod nervous system • Cephalopods (esp. coleoids) are known to be the most intelligent invertebrates. • Spatial learning capacity • Navigational abilities • Predatory techniques • Nervous system affects chromatophores

  13. The cephalopod nervous system • The squid giant axon: • Up to 1 mm thick • Unmyelinated, unlike in vertebrates • Branches out from the stellate ganglion • Innervates the mantle of the squid • Responsible for mantle contractions – thus, forcing water through the hyponome. • http://www.youtube.com/watch?v=omXS1bjYLMI

  14. The cephalopod nervous system • The squid giant synapse: • Largest chemical junction in nature • Identified by J. Z. Young in 1939 • Lies in the stellate ganglion • A chain of three neurons • Relays input from cephalic ganglion (the squid’s brain) to the mantle.

  15. The cephalopod nervous system

  16. The cephalopod nervous system

  17. The cephalopod circulatory system • A closed circulatory system • Relies on haemocyanin rather than haemoglobin to transport oxygen • Colourless blood turns blue when exposed to air • Coleoids (squids, cuttlefish and octopuses) have two branchial hearts (also known as gill hearts) and one systemic heart which pumps blood around the body.

  18. The cephalopod circulatory system • Note copper prosthetic groups coordinated by histidine residues. • In environments with low temperature and low oxygen pressure, haemocyanin is more efficient than haemoglobin. • Haemocyanin is not bound to red blood cells, but rather are suspended in the haemolymph.

  19. Chromatophores • Soft-bodied cephalopods rely heavily on camouflage to escape detection by predators • Colour patterns of cephalopods are largely controlled by chromatophores in the dermis • Each chromatophore is a miniature organ consisting of a single pigment-filled saccule and numerous muscle, nerve, glial and sheath cells

  20. Chromatophores

  21. Chromatophores • Melanin pigments are yellow, orange, red or brown • Saccules darken with age, presumably due to increased zinc content • When attached muscles contract, the pigment-containing saccule will stretch to cover a larger area, displaying the pigment • Relaxation of muscles causes the saccule to shrink, hiding the pigment

  22. Chromatophores • Each chromatophore is directly controlled by the brain (via associated neurons), enabling: • Generation of complex patterns • Extremely rapid response to stimuli

  23. The cephalopod eye • Most sophisticated of all invertebrate eyes • As complex as and structurally similar vertebrate eyes (single-lens), but not homologous • During organogenesis, the vertebrate eye develops as an extension of the brain • The cephalopod eye develops from the head surface

  24. The cephalopod eye Vertebrate (human) eye Cephalopod (octopus) eye

  25. The cephalopod eye • Able to detect polarised light • Hunting prey – light becomes polarised when reflected off fish scales • Covert communication using patterns of polarised light on their skin Photoreceptors in a cephalopod eye

  26. The cephalopod eye Octopus Squid Cuttlefish Nautilus

  27. The squid and the cuttlefish • What are the differences? • The squid is of the order Teuthida; the cuttlefish is of the order Sepiida. • The squid is torpedo-shaped; the cuttlefish is broader and more flattened. • The squid has a chitinous squid pen; the cuttlefish has a porous cuttlebone. • The squid moves much more swiftly than the cuttlefish, which relies more on camouflage.

  28. The squid and the cuttlefish • Interesting squid facts: • Deep water squid have the second greatest known penis length relative to body size • The squid systemic heart has 3 chambers. • Squid ink is used in making Arròs negre. • Some male squids can detach an arm and use it to transfer sperm to the female.

  29. The squid and the cuttlefish • Interesting cuttlefish facts: • All cuttlefish contain neurotoxins. • Cuttlefish have some of the largest brain-to-body size ratios. • The colour name sepia comes from the Greek and Latin word for “cuttlefish”. • Lateral lines allow it to detect sound – it can hunt with 50% accuracy in total darkness • The Pfeffer’s Flamboyant Cuttlefish is as toxic in its muscles as the Blue-Ringed Octopus.

  30. The squid and the cuttlefish • Interesting squids: • Colossal Squid (Mesonychoteuthis hamiltoni) • Crachiid Squid (family Cranchiidae) • Cock-eyed Squid (family Histioteuthidae) • Promachoteuthis sulcus • Piglet Squid (Helicocranchia sp.) • Firefly Squid (Watasenia scintillans)

  31. The squid and the cuttlefish

  32. The bobtail squid • Closely related to cuttlefish • Rounded mantle and no cuttlebone • Symbiotic relationship with bioluminescent bacteria, Vibrio fischeri. • Certain species bury themselves in sand. • http://www.youtube.com/watch?v=eB-M4adJIeY

  33. The octopus • Interesting octopus facts: • Chemoreceptors on suction cups allow them to taste what they are moving across • Most are semelparous and exhibit unnatural, non-coordinated behaviour (senescence) after mating, eventually starving to death • This is controlled by endocrine secretions from the optic glands

  34. The octopus • Interesting octopuses: • Blanket Octopus (Tremoctopus spp.) • Vulcanoctopus hydrothermali • Paper Nautilus (Argonauta spp.) • Mimic Octopus (Thaumoctopus mimicus)

  35. The nautilus • Interesting facts about nautiluses: • Two pairs of gills; thus called tetrabranchs. • Shell is an example of logarithmic spiral. • Considered living fossils • Radula have nine teeth. • The osmena pearl is derived from the shells. • Lifespan of up to twenty years.

  36. The nautilus

  37. Thank you!! :DDD Um.

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