Cephalopods

Class Cephalopoda ^[1]
- Includes octopuses, cuttlefish, squid, etc^[1]
- Present in all the world's oceans ^[1]

Evolution

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]
Life Cycle
- No true larval stage ^[2]
- Large eggs hatch as paralarvae ^[1]
- Adult size reached in about one year ^[1]
- Most individuals die shortly after mating ^[1]
- Uniseasonal breeding ^[1]
  - Can cause considerable seasonal fluctuations in population ^[1]

Buccal cavity ^[2]
Radula ^[2]
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 and colors 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]

Rapid color change ^[3]
Centralized brain with highly developed sense organs ^[3]
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]

↑ ^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 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>.
↑ ^2.00 ^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 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/>.
↑ ^3.0 ^3.1 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>
↑ ^4.0 ^4.1 ^4.2 ^4.3 ^4.4 ^4.5 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>.