Cephalopods

From coraldigest
Revision as of 00:55, 26 February 2014 by BBenson (talk | contribs)
Jump to: navigation, search

Cephalopods

  • All are molluscs
  • Class Cephalopoda [1]
    • Includes octopuses, cuttlefish, squid, etc[1]
    • Present in all the world's oceans [1]

Evolution

  • Probably evolved from gastropods [2]
  • More than 10,000 fossil species named [2]
  • Belemnoids, from the Mesozoic, may be the ancestors of modern squids [2]

Life Cycle and Reproduction

Males

  • Specialized arm or tentacle that transfers spermatophores to the female's genital pore [2]
    • This specialized appendage is sometimes left behind in the female's mantle cavity (known as a hetocotylus arm) [2]

Females

  • Single oviduct [2]
  • Courtship rituals can include color changes and body movements [2]
    • Females may mate with multiple males and have multiple paternity of offspring [1]

Life Cycle

    • Eggs are covered in a touch coating that attach to hard surfaces [1]
      • Hatch directly into "paralarvae," which are essentially mini adults, but may occupy different ecological niches than adults [1]
      • Some octopuses stay with eggs and guard them while others spawn in open water [1]
  • No true larval stage [2]
  • Large eggs hatch as paralarvae [1]
  • Adult size reached in about one year [1]
    • Sexual maturation occurs rapidly [1]
    • Most individuals die shortly after mating once [1]
    • Uniseasonal breeding [1]
      • Can cause considerable seasonal fluctuations in population [1]
        • These fluctuations are highly variable and inconsistently patterned

Anatomy

  • Buccal cavity [2]
  • Radula [2]
    • Coarse, rasping tongue [3]
  • Ink gland [2]
  • All but the family Nautilus have cells containing large amounts of pigment and contractile fibers [2]
    • This is what enables the animals to change colors [2]
      • Frequently occurs in response to danger or emotion
  • Can distinguish shapes with highly evolved sensory system
  • Have reduced or absent calcareous shells [1]
  • Squids and octopuses have lost the internal shell and its buoyancy functions [1]
  • Brain
    • Ganglionic masses centered around the esophagus [1]
  • Well developed statocysts (gravity and movement senses) [1]
  • Skin
    • Delicate epithelial tissue over layers of connective tissue [1]
    • Chromatophores [1]

Diet

  • Carnivorous [2]
    • Feed on wide range of crustacea and fish[1]
    • Eat approximately 1.5 and 15% of body weight daily [1]
    • Some exhibit cannibalism on smaller members of their [1]respective species [1]
    • Prey are usually attacked with a forward strike and subsequently pulled toward the mouth with tentacles [1]
    • Squid bite their prey with their beaks [1]
    • Octopuses have a more complicated means of consuming their prey [1]
      • Secretion of toxins/enzymes is injected into the prey [1]
        • Makes the flesh easier to extract from crustaceans [1]

Behavior

  • Rapid color change [4]
    • Most frequently used for crypsis (camouflage), mating displays, and prey/predator response[1]
      • Great evolutionary significance [1]
  • Centralized brain with highly developed sense organs [4]
  • Jet propulsion [2]
    • Using the muscular mantle to force water through the ventral funnel [1]
    • Coastal octopuses are more benthic in nature [1]
      • Use their arms to move around the ocean floor, only occasionally employing jet propulsion [1]
  • Inking [1]

Habitat

Importance

Economic value

  • Many species are eaten by humans[2]
    • This goes back as far as classical times [1]
    • As many as 3 million tonnes are consumed annually by humans [1]
    • Commercial harvest has increased from about 1 million tonnes to 3 million tonnes from the 1970s-1990s

Ecological value

  • Important to food chain [1]
    • Eat a wide variety of fish, crustaceans, and other invertebrates [1]
    • Preyed upon by fish, marine mammals, and oceanic birds [1]
      • Cephalopod remains are often found in the guts of large fish, seals, whales, and birds [1]
        • Sperm whales may consume up to 320 X 10^6t of cephalopods from open ocean areas [1]

Threats

Human Induced Threats [5]

  • Bioaccumulation of toxins [5]
  • Noise pollution [5]
  • Altered seasonal migration patterns related to ocean warming [5]
  • Possible decrease in availability of calcium carbonate, related to declining pH [5]
  • Overfishing [5]

Species

Common Octopus [6]

  • Geographic Range
  • Habitat
  • Physical Appearance
  • Reproduction and Development
  • Behavior and Diet
  • Conservation Status

Caribbean Reef Squid [7]

  • Geographic Range
  • Habitat
  • Physical Appearance
  • Reproduction and Development
  • Behavior and Diet
  • Conservation Status

Caribbean Reef Squid [8]

  • Geographic Range
  • Habitat
  • Physical Appearance
  • Reproduction and Development
  • Behavior and Diet
  • Conservation Status

Caribbean Two-Spot Octopus [9]

  • Geographic Range
  • Habitat
  • Physical Appearance
  • Reproduction and Development
  • Behavior and Diet
  • Conservation Status

Notes

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40 Boyle, P. "Cephalopods." Encyclopedia of Ocean Sciences 1 (2001): 436-42. Science Direct. Elsevier B.V., 11 Apr. 2013. Web. 22 Feb. 2014. <http://ac.els-cdn.com/B9780123744739001958/3-s2.0-B9780123744739001958-main.pdf?_tid=4e6f9af6-9e64-11e3-bd04-00000aacb360&acdnat=1393364120_b8c509396a239367521c18e75d90ee5a>.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 Wheeler, Kristen, and Daphne G. Fautin. "ADW: Cephalopoda: INFORMATION." Animal Diversity Web. Regenst of the University of Michigan, 2001. Web. 22 Feb. 2014. <http://animaldiversity.ummz.umich.edu/accounts/Cephalopoda/>.
  3. ↑ Judkins, Heather L. "Cephalopods of the Broad Caribbean: Distrution, Abundance, and Ecological Importance." Diss. University of South Florida, 2009. Scholar Commons. Graduate School at Scholar Commons. Web. 21 Feb. 2014. <http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3033&context=etd&sei-redir=1&referer=http%3A%2F%2Fwww.google.com%2Furl%3Fq%3Dhttp%253A%252F%252Fscholarcommons.usf.edu%252Fcgi%252Fviewcontent.cgi%253Farticle%253D3033%2526context%253Detd%26sa%3DD%26sntz%3D1%26usg%3DAFQjCNF6Q0NU3If5jMRKW7UQ1KtCo117qQ#search=%22http%3A%2F%2Fscholarcommons.usf.edu%2Fcgi%2Fviewcontent.cgi%3Farticle%3D3033%26context%3Detd%22>.
  4. ↑ 4.0 4.1 Jann, Vendetti. "The Cephalopoda." University of California Museum of Paleontology. UC Berkeley, n.d. Web. 24 Feb. 2014. <http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/cephalopoda.php>
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 LaRosa, Ginni A.. "Learning from the Soft Intelligence: Cephalopods as Indicators of Ocean Changes." UMD Library. University of Maryland, 01 Dec 2011. Web. 25 Feb 2014. <http://drum.lib.umd.edu/bitstream/1903/12427/11/LaRosa_ResearchPaper.pdf>.
  6. ↑ Case, R. 1999. "Octopus vulgaris" (On-line), Animal Diversity Web. Accessed February 25, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Octopus_vulgaris/
  7. ↑ Ritter, S. 2000. "Sepioteuthis sepioidea" (On-line), Animal Diversity Web. Accessed February 25, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Sepioteuthis_sepioidea/
  8. ↑ Robinson, A. 2000. "Octopus briareus" (On-line), Animal Diversity Web. Accessed February 25, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Octopus_briareus/
  9. ↑ Tokarz, Jessica. " Caribbean Two-Spot Octopus." Field guide to marine inhabitants - Invertebrates. Marine Science Center of Florida. Web. 25 Feb 2014. <http://www.marinesciencecenter.com/Octopodidae.htm>.
Retrieved from "https://www.coraldigest.org/index.php?title=Cephalopods&oldid=2875"
Cookies help us deliver our services. By using our services, you agree to our use of cookies.
More information