CephalopodsCephalopodsCorresponding Reading Material

~ Squid section in Lab Manual

~ Levinton: Chapter 8

The Phylum MolluscaThe Phylum MolluscaGeneral Characteristic:General Characteristic:

1. Bilaterally symmetrical1. Bilaterally symmetrical2. Possess a mantle which secretes the shell2. Possess a mantle which secretes the shell3. muscular foot 3. muscular foot 4. radula (file-like feeding structure); modified in some 4. radula (file-like feeding structure); modified in some classesclasses5. Possess a one way gut 5. Possess a one way gut 6. Reproduces sexually6. Reproduces sexually

There are 7 different classes within the mollusk phylum:There are 7 different classes within the mollusk phylum:~ Class ~ Class PolyplacophoraPolyplacophora - Chitons - Chitons ~ Class ~ Class AplacophoraAplacophora - Mollusks without shells - Mollusks without shells ~ Class ~ Class MonoplascophoraMonoplascophora - Mollusks with one shell - Mollusks with one shell ~ Class ~ Class SchapodaSchapoda - Mollusks with a tubular shell - Mollusks with a tubular shell ~ Class Gastropoda - Gastropods, snails and their relatives ~ Class Gastropoda - Gastropods, snails and their relatives ~ Class Bivalvia - Bivalves ~ Class Bivalvia - Bivalves ~ Class Cephalopoda - Cephalopods, squids and octopuses ~ Class Cephalopoda - Cephalopods, squids and octopuses

The Class The Class CephalopodaCephalopoda

General Characteristics:General Characteristics:

1. A funnel derived from the molluscan foot 1. A funnel derived from the molluscan foot

2. Chitinous beaks 2. Chitinous beaks

3. Complex eyes. 3. Complex eyes.

4. Have a head surrounded by a foot divided into arms4. Have a head surrounded by a foot divided into arms

5. Are carnivorous5. Are carnivorous

6. Well organized nervous system6. Well organized nervous system

7. Have complex behaviors7. Have complex behaviors

Are the most highly evolved mollusks and invertebrates.

Cephalopod EvolutionCephalopod Evolution The earliest cephalopods were shelled mollusks that were The earliest cephalopods were shelled mollusks that were

probably similar to limpets. They appeared 500 million years ago probably similar to limpets. They appeared 500 million years ago during the Upper Cambrian Period.during the Upper Cambrian Period.

The ammonite with its coiled shell appears in the Devonian period The ammonite with its coiled shell appears in the Devonian period around 400 mya same time as sharks). This organism shows a around 400 mya same time as sharks). This organism shows a great advancement in mobility. Ammonites continued with great advancement in mobility. Ammonites continued with numerous developmental variations and became the dominant numerous developmental variations and became the dominant cephalopod until the end of the Cretacious period about 144 mya.cephalopod until the end of the Cretacious period about 144 mya.

The driving force of the extensive evolutionary change seems to The driving force of the extensive evolutionary change seems to be related to the changes in the continental configuration be related to the changes in the continental configuration between 500 and 140 mya. These changes brought about severe between 500 and 140 mya. These changes brought about severe alterations in climate, major reconfigurations of continental alterations in climate, major reconfigurations of continental shelves, reduction in estuaries and wetlands, and changes in shelves, reduction in estuaries and wetlands, and changes in oceanic current patterns. oceanic current patterns.

The NautilusThe Nautilus

The nautilus is different from many of the The nautilus is different from many of the other cephalopods because it has retained other cephalopods because it has retained its shell.its shell.

The Diversity of The Diversity of CephalopodsCephalopods

Today there are approximately 650 different species of cephalopods.

Ecology of CephalopodsEcology of Cephalopods

Cephalopods are strictly marine. They usually live in the deeper waters Cephalopods are strictly marine. They usually live in the deeper waters of the ocean, but some species are known to live in shallower waters.of the ocean, but some species are known to live in shallower waters.

They are found from the warm waters of the tropics to the near They are found from the warm waters of the tropics to the near freezing waters by the poles.freezing waters by the poles.

Most species are nektonic (live in the water column far above the sea Most species are nektonic (live in the water column far above the sea floor)floor)

All cephalopods are predators. They use tentacles to capture prey, and All cephalopods are predators. They use tentacles to capture prey, and they have beaks that tear apart the flesh.they have beaks that tear apart the flesh.

The Blue Ring The Blue Ring OctopusOctopus

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It lives in warm, shallow reefs off the coast of Australia, New Guinea, Indonesia, and the Philippines.

It has a life span of about 1.5 years.

The Blue Ring Octopus is the most venomous octopus.

It catches prey with its arms, bites it with its tough beak, and kills it by delivering a poison in the saliva. The poison is a neurotoxin that is strong enough to kill a human.

The Giant Pacific OctopusThe Giant Pacific Octopus largest species of octopus in the largest species of octopus in the

world. Most individuals weigh less world. Most individuals weigh less than 100 lbs but an individual than 100 lbs but an individual captures near Victoria, British captures near Victoria, British Columbia in 1967 weighed 156 lbs. Columbia in 1967 weighed 156 lbs. and was almost 23 ft from arm tip to and was almost 23 ft from arm tip to arm tip.arm tip.

mainly lives on the continental shelf mainly lives on the continental shelf of the north Pacific ocean.of the north Pacific ocean.

After hatching, the Giant Pacific After hatching, the Giant Pacific Octopus swims towards the surface Octopus swims towards the surface and spends 4-12 weeks drifting in the and spends 4-12 weeks drifting in the plankton until it reaches a size of plankton until it reaches a size of >14mm.>14mm.

They typically live 3-5 years.They typically live 3-5 years.

The Giant SquidThe Giant Squid the largest invertebrate to ever live the largest invertebrate to ever live

on Earth. No one has ever seen a on Earth. No one has ever seen a giant squid alive in its own habitat. giant squid alive in its own habitat.

Scientists know of their existence Scientists know of their existence through the study of specimens found through the study of specimens found in the stomachs of sperm whales, in the stomachs of sperm whales, washed up on beaches, or caught in washed up on beaches, or caught in fishermen’s nets.fishermen’s nets.

can grow up to 21.3m (70ft.) long. can grow up to 21.3m (70ft.) long. Their arms alone can grow to be 10 Their arms alone can grow to be 10 feet long while their tentacles can feet long while their tentacles can extend as far out as 36 feet. extend as far out as 36 feet.

They can weight up to 4 metric tons. They can weight up to 4 metric tons.

The Color Changing The Color Changing CuttlefishCuttlefish

Cuttlefish, and other cephalopods change colors by using Cuttlefish, and other cephalopods change colors by using chromatophores. All of this is under the control of the cuttlefish’s chromatophores. All of this is under the control of the cuttlefish’s advanced nervous system. When the muscles are relaxed, the advanced nervous system. When the muscles are relaxed, the surface area of the sac is small and the color is not expressed. When surface area of the sac is small and the color is not expressed. When the muscles contract the surface area becomes much greater and the muscles contract the surface area becomes much greater and the color is seenthe color is seen. .

Cuttlefish use the change in color for mating purposes and to Cuttlefish use the change in color for mating purposes and to communicate.communicate.

Cephalopod BehaviorsCephalopod BehaviorsNavigation and Spatial Maps:Navigation and Spatial Maps: species species Octopus vulgaisOctopus vulgais found in Bermuda is found in Bermuda is

a cental place forager- uses a spatial map.a cental place forager- uses a spatial map. finds and lives in homes of shells, beer finds and lives in homes of shells, beer

bottles, or sheltered niches. environment. bottles, or sheltered niches. environment.

This same species of octopus also seems to This same species of octopus also seems to cover different parts of its home range one cover different parts of its home range one after another on subsequent hunts and days after another on subsequent hunts and days which suggests they also have a working which suggests they also have a working memory.memory.

Cephalopod BehaviorsCephalopod Behaviors

““Playing” behavior:Playing” behavior:

A group of A group of Octopus Octopus at the Seattle Aquarium were at the Seattle Aquarium were subjected to 10 trials over 5 days. On the first trial subjected to 10 trials over 5 days. On the first trial each was given a floating bottle. During this trial each was given a floating bottle. During this trial all the individuals grabbed the bottle and brought all the individuals grabbed the bottle and brought it to their mouths. Several of the octopuses jetted it to their mouths. Several of the octopuses jetted water at the bottle during later trials. But two of water at the bottle during later trials. But two of the octopuses aimed water jets that made it circle the octopuses aimed water jets that made it circle the tank and come back to them for further jets. the tank and come back to them for further jets. One octopus set it up so that the bottle circled the One octopus set it up so that the bottle circled the tank for a round trip time of 2 minutes. The other tank for a round trip time of 2 minutes. The other made it return every 30 seconds.made it return every 30 seconds.

ConservationConservation Currently cephalopods have no Currently cephalopods have no

conservation status conservation status

Very little known about cephalopod natural Very little known about cephalopod natural history.history.

The California Department of Fish and The California Department of Fish and Game recommended a management plan Game recommended a management plan for the squid fishing industry. This plan was for the squid fishing industry. This plan was signed into law on September 20, 2001.signed into law on September 20, 2001.

The Australian Giant Cuttlefish’s population The Australian Giant Cuttlefish’s population was decimated in 1997 and 1998. In 1998 was decimated in 1997 and 1998. In 1998 the commercial season was closed early the commercial season was closed early and a complete closure occurred in 1999 and a complete closure occurred in 1999 and 2000.and 2000.

concerned local sport divers have rallied to concerned local sport divers have rallied to establish permanent refuges and long-term establish permanent refuges and long-term conservation plans.conservation plans.