Aliens in Our Oceans: Cephalopods
Topic Overview

Main Concepts
Target Audience
Synopsis
Standards
Suggestion for Student Engagement
Background Information
Resources

Enduring Ideas/ Main Concepts:

Animal Adaptations and how they lead to Species Diversity: Organisms develop characteristics that help them survive and reproduce. Animal characteristics change through various mechanisms: from exchange of genetic materials during reproduction and sometimes by random mutations that prove to be beneficial. Any characteristic that helps an organism avoid predation or compete successfully for food, housing or mates, is considered an adaptation. These new improved characteristics are called adaptations, which typically change and evolve over time. If the organism fails to adapt to changes in its environment, or migrate to another environment, then it may not reproduce, which may eventually result in the species becoming extinct.

Target audience:

Grades 5-8. The depth of investigations and level of difficulty can be increased or decreased as the teacher finds appropriate for their individual students and Teachers may choose to modify the product or performance task expectations as developmentally appropriate for the age group. The teacher can also modify the suggested assessments to meet curriculum goals. Text, video and Internet resources are provided at the end of this overview to support teacher planning.

Synopsis:

This group of lessons explores cephalopods as a conduit to understanding adaptation and how organisms evolve over time by developing traits that help them to survive and reproduce. The unit addresses species diversity within a specific group of organisms that are closely related, and addresses how and why those organisms have evolved various traits. Included are extensions that provide opportunity to research the following:

• The four types of animals within the class Cephalopoda
• Provide students insight into heritable traits, internal and external characteristics
• How related animals have developed differently in order to adapt to their individual environments
• Discussion of sensory and behavioral evolution within this class of invertebrates

Included are writing opportunities, integration of mathematics, literary connections and suggestions for integration into social studies and other curricula. The lessons suggest more than one strategy to achieve the objectives of the lesson allowing teachers to choose which strategy satisfies the specific needs of their class. Or teachers may choose to pilot a strategy they are less familiar with in order to facilitate a wide array of learning opportunities for their students.

Technology
These lessons are designed so that they can be implemented in schools at any level of technological capacity. Activities vary from simple to complex, and range from text-based to entirely web-based.

Benchmarks/Standards:

Benchmarks and National Science Education Standards (NSES) are addressed in each lesson plan. These lessons were written using the NSES as the primary focus.

Suggestion for Student Engagement:

Ask the class: Are cephalopods Aliens?

Of course they are not aliens, but if ever there were a group of organisms that could be described as alien, it would be cephalopods:

• They are NAKED mollusks: no external shell (except Nautiluses).
• They are ALL predators, even though they are invertebrates.
• They have no armor! And yet they defend themselves successfully.
• They may live in remote areas: rocky intertidal , the open ocean, or the abyss.
• They can change color, texture and shape just by thinking about it.
• Some can change the texture of their skin so that they can hide more effectively.
• They can regenerate lost limbs.
• They have three hearts, pump blue blood and an esophagus that goes through the brain!.
• They have superior senses, well developed brains and they like to play games. And win!
• They reproduce once, and then they die (usually).
• They have been called an evolutionary dead end, since they are the most highly developed invertebrates. They may be as good as it gets without a skeleton.

Background Information for the teacher:

See: http://www.thecephalopodpage.org/, then scroll down to the ‘Introduction to Cephalopods’ for more general information. There are numerous links to detailed information and a link to FAQs as well.

Cephalopods are an ancient molluscan class of animals that include a diverse collection of >650 species of octopuses, cuttlefish, squid and nautilus. They that inhabit every ocean and are active, intelligent marine predators that possess the most well developed senses of all invertebrates. Cephalopoda is derived from ancient Greek, meaning “head-footed”, because their arms are connected to their head, not their bodies; the rest of the body is in front of the head. The basic body plan is elongated and includes:

• Mantle: a leathery outer skin
• Mantle Cavity: visceral mass that houses the internal organs
• Modified muscular “feet”: aids movement and grasps prey; varies with each type.
• Radula: a tongue-like feeding structure equipped with rasping “teeth”

Unlike most mollusks, cephalopods lack a shell, except for Nautiluses, which are swimming snails! They are living fossils: slow, primitive and long-lived. Squid and Cuttlefish lead active lives and have internal shell-like components. Octopuses are reclusive and only become active to hunt or mate, typically hiding, motionless for >20 hours a day. All cephalopods have beak-like structures paired with a radula, a rasping tongue for feeding. The muscular foot of the mollusks has evolved into a siphon and arms, commonly called tentacles – 8 for octopuses, 10 for squid, and up to 90 for nautilus!

Cephalopods possess an amazing array of unique abilities that together compensate for the lack of armor and provide nearly perfect disguise:

• They can change the color and texture of their skin for camouflage.
• They change shape by manipulating their soft bodies.
• They produce “ink” to confuse predators.
• They jet backwards by forcing water from the siphon to escape predation.
• They have the most highly developed vision of all invertebrates, similar to vertebrates, with a cornea, lens and retina.
• They can see images, unlike other invertebrates.

All cephalopods have well-developed nervous systems and superior senses to support active life styles and rapid movement. Although they do not see in color, they see very well in low light conditions and most are nocturnal. Their brains have distinct lobes with a brain to body weight ratio that exceeds that of fish and reptiles. They are curious animals that explore their environment and are capable of learning, and will play with objects for no apparent reason except to amuse themselves.

Cephalopods exist in an amazing range of size, from 5mm to more than 15m in length. The giant squid Architeuthis, for example, lives in the North Atlantic and is the largest invertebrate on earth. Individual tentacles may measure > 6m, and the eye may be 30 cm across, the size of an automobile hubcap. They swim the open ocean and have never been observed alive in the wild.

Cephalopods typically have a very short lifespan, ranging from 6 months to 2 years. Smaller tropical species tend to have shorter lives while larger, cold-water species live longer. To compensate for the fast pace of their lives, they grow very fast, exhibiting exponential growth when they are young; they may increase their body weight by 10% per day! Most mollusks have very small, planktonic offspring in enormous numbers, but cephalopods have fewer and larger offspring, and some do not have a planktonic phase. Most curious, cephalopods exhibit semelparity: they reproduce once and then they die. It can be said that they live fast, and then they die!

An amazing diversity of species that possess superior senses, demonstrate masterful disguise and short, active lives defines this group of animals. Although they may be alien compared with terrestrial animals, they are exquisitely designed for life in the sea.

Resources:

There are three websites that together reveal most of what a teacher needs to know about these animals. They are all student friendly as well.

The Cephalopod Page http://www.thecephalopodpage.org/

This is the most useful resource available for these animals! This page is maintained by Dr. James Woods, one of the most knowledgeable scientists in the world regarding Cephalopods, and a premier photographer of these animals. This website contains background information, image gallery and additional resources for both the teacher and the student. It has links to many articles about this class of animals, both as a class and individually, including numerous photos. There is a phylogenic tree that traces the relationships within the class Cephalopoda.

Ocean Links http://oceanlink.island.net

This is very complete online resource and it is edited by scientists, so the information is current and accurate. It contains a complete Marine glossary, pages regarding specific species as well as general topics such as the deep sea, hydrothermal vents and bioluminescence. The most useful feature is called Ask the Scientists, which allows individuals to ask questions and have the answers posted on the website. It also has an archive that is extensive. Link to “Ask the Scientists” then go to “Archive”; copy and paste the entire list onto a new page, and you have an instant cephalopod resource. Teachers will find the questions asked convenient prompts for class discussion/debates. This website also contains a list of Marine Labs & Institutions worldwide with hyperlinks to those sites. Students may use the website as well for WebQuest type investigations.

Smithsonian Museum www.educate.si.edu/science_and_technology

The Smithsonian has numerous resources for teachers. This site contains an exhibit called OceanPlanet and another discussing Galapagos Islands that relates to this topic. There is an area called Explore & Learn that is geared to students. The most useful feature of this website is its own search engine for the >40 institutions that are part of the Smithsonian. It is called SIRIS (Smithsonian Institute Research Information System) and has its own URL: www.siris.si.edu. For example, if you scroll down to Specialized Research Bibliographies, and enter Cephalopods as a search word, you get 670 references.

* Remember to save any documents that you intend to use: museums remove material from their sites on occasion or move them, and you may not be able to retrieve them later.

WEB-BASED:

Aquariums Around the World http://aquae.com/

Global aquatic web service with ultrafast links to aquariums, educational resources, images & databases. A lot of useful information.

Biodiversity http://wri.igc.org/wri/biodiv/

World Resources Institute has a number of web pages that address biodiversity in general, and also contain information specific to ocean environments; very extensive resource. Topics included species estimates, coral reefs, facts & figures regarding animal species, marine data tables, forestry issues, climate influences, sustainable development, threats to biodiversity, etc. Includes book and video resources.

CephBase http://www.cephbase.utmb.edu/

Premier photo resource for cephalopods! Photos and information is gathered and posted by Dr. James Wood, University of Texas, Galveston, TX, the research specialist for this unit. He has photos and videos featuring cephalopods from around the world taken during his own research and that of many other researchers world-wide.

National Aquarium in Baltimore www.aqua.org/animals/species

This aquarium has excellent information, available by species in some cases. May be used by students since it is easy to navigate. Contains an overview of cephalopods that is exemplary.

National Geographic/Sustainable Seas

New Jersey Marine Science Consortium http://www.njmsc.org/

This website includes a virtual tour of a research vehicle used at sea; includes what and how research vehicles are employed by scientists. Useful to increase student engagement at the beginning of the unit. Click on Marine operations and then look for link for virtual tour on the left.

Ocean animal topics http://mbgnet.mobot.org/salt/animals/mollusk.htm

Includes a useful overview of many animals by class. Includes clear, colorful photos and general descriptions. Good starting point for unfamiliar animals.

Pulse of the Planet http://pulseplanet.nationalgeographic.com/ax/archives_index.html

The archives contain several articles regarding giant squid that are very current.

Royal British Columbia Museum http://rbcm1.rbcm.gov.bc.ca/notes/squid

Comprehensive description of squid and brief historical perspective. Includes a drawing that can be enlarged and printed.

Scientific American: Ask an Expert www.sciam.com/askexpert

This website maintains an extensive archive of previously asked questions. You may also search by topic. Easy to navigate for students.

Tree of Life Web Project http://tolweb.org/tree/home.pages/searchTOL?taxon=Cephalopod&Submit=Find&wordpart=partial

Classification and general descriptions of cephalopods. Easy to understand phylogenic tree that can be cut and pasted into a new document.

TEXT-BASED:

Carolina Biological Supply Company

Catalogue includes preserved specimens, specimens in Lucite, and squid study guide with reproducible black-line illustrations.

Marine Biology, second Ed. Peter Castro & Michael E. Huber. Dubuque, IA: Wm. C. Brown Publishers. 1997.

Octopus and Squid: The Soft Intelligence. Jacques-Yves Cousteau and Phillippe Diole. Garden City, NY: Doubleday & Co. 1973.

Describes Captain Cousteau’s experiences with these marine animals. Although an older resource, the observations are factual, written in narrative form and still useful.

Tentacles: The Amazing World of Octopus, Squid and their Relatives. James Martin. Crown. 1993.

A detailed resource for these animals and well written.

The Search for the Giant Squid. Richard Ellis. New York: The Lyons Press. 1998

An excellent resource for information about giant squ