I recently saw a documentary on Discovery Channel about the behavior of the octopus, Octopus Vulgaris, and decided to look for the video and share with everyone how amazing this “quick-change” artist is.

Actually, the octopus belongs to the class, cephalopod, which also includes cuttlefish, squid and nautiluses. Animals in this class are said to be able to change their body colours even faster than a chameleon.

Cephalopods exhibit different types of body patterns for different situations. As mentioned in the first video, it is an important way of communication, be it with fellow species, their prey or predators.

The different body patterns on the octopus are brought about by the dual action of thousands of chromatophores, which are small pigmented organs (subjectively classified into two or three colour classes per species: red, yellow/orange, and brown/black), and by light-reflecting cells. These chromatophores are attached to dozens of radial muscles that are innervated directly by the visual part of the brain, and by contracting and relaxing these muscles, the pigmented sac of a chromatophore increases or decreases in area and hence enables cephalods to produce an array of body-patterning components, such as bands, strips and spots.

From the Video:

0:08: Mating of cuttlefish. The male cuttlefish displays a “range of tones” to attract the female cuttlefish

0:35: “strange and rhythmic pulsing” by the cuttlefish – “the passing cloud”. Cuttlefish use this technique to mesmerize their prey and hence making them an easy target.

1:07: The blue ring octopus, Hapalochlaena lunulata and Hapalochlaena maculos, is highly venomous. One bite from the octopus is enough to kill. Hence, the octopus emphasizes this fact by using “vivid warning colours” – the blue rings.

1:33: My favourite part of the video. The way that the octopus protects itself from predators is very intriguing, especially the one shown in the video. The octopus first camouflages itself on the rock, so well that you do not notice it. When the predator comes too close for comfort, the octopus reveals itself and spreads out its tentacles to appear bigger than more intimidating. Then it darts away, leaving a trail of “inky smoke screen” that is foul-tasting.

2:05: Octopuses can not only change their body colour but also their body texture so as to completely blend into its surroundings. “It can blend with any background.”

2:57: One of the most threatening displays of bluff – “the owl face”. The octopus only reveals its face, to imitate a bigger animal, such as the stingray.

According to research and the video, octopuses have cognitive abilities. In the first experiment, the octopus is able to recognize the layout of the maze. In the second experiment, the octopus is able to recognize the shapes and remember that the food is behind the cross shape.

Master of Shape change

The last part of the video mentions a bit about the Indonesian Mimic Octopus, Thaumoctopus mimicus. This species of octopus is known to be the best imitator of other sea animals. The second video demonstrates the three types of sea animals that the mimic octopuses usually imitate.

0:53 – flounder. The flounder has toxic in its skin, hence predators would avoid it. The octopus imitates the flounder by drawing “all of its arms together into a leaf-shaped wedge as it undulates in the manner of a swimming flat fish”. (marinebio.org)

1:35 – lion fish. The lion fish’s fins tips have venom, hence predators learn to avoid them too. “The octopus hovers above the ocean floor with its arms spread wide, trailing from its body to take on the appearance of the lion fish’s poisonous fins.” (marinebio.org)

2:13 – sea snake. The sea snake uses its venom to imobilize its prey. The octopus changes colour, taking on the yellow and black bands of the toxic sea snake as it waves 2 arms in opposite directions in the motion of two sea snakes. (marinebio.org)

0:33: the amazing speed of colour change when the octopus is threatened.

       “This animal is so intelligent that it is able to discern which dangerous sea creature to impersonate that will present the greatest threat to its current possible predator. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.”

–       Marinebio.org

Resources

“Dangers on the Reef…..Blue Ring Octopus“, by barrierreefaustralia.com. URL: http://www.barrierreefaustralia.com/the-great-barrier-reef/blueringedoctopus.htm (accessed on 01 Apr 2010).

“Hawaiian Marine Life Profiles: Invertibrates – Octopus“, by Maui Ocean Centre. URL: http://www.mauioceancenter.com/index.php?id=11&ss=0&page=marine&content=marine_detail&cat=2&CRid=31&limitstart=0 (accessed on 01 Apr 2010).

“Introduction to Cephalopods“, by The Cephalopods Page. URL: http://www.thecephalopodpage.org (accessed on 01 Apr 2010).

“Octopus camouflage“, by oldenhaller. YouTube.com, 02 Feb 2008.  URL: http://www.youtube.com/watch?v=jN99Kx_ghC8&feature=PlayList&p=59D36CEBC472A154&playnext_from=PL&playnext=1&index=30 (accessed on 01 Apr 2010).

“Malleable skin coloration in cephalopods: selective reflectance, transmission and absorbance of light by chromatophores and iridophores”, by Lydia M. Mäthger & Roger T. Hanlon. Springerlink, 05 Apr 2007. URL: http://www.springerlink.com.libproxy1.nus.edu.sg/content/b22635n5227245w6/fulltext.html (accessed on 01 Apr 2010).

“The Indonesian Mimic Octopus” by marcelnad. YouTube.com, 01 Feb 2008.  URL: http://www.youtube.com/watch?v=H8oQBYw6xxc&feature=related (accessed on 01 Apr 2010).

In the vast and wide Animal Kingdom, newborn young of egg-laying species are often left by their parents to fend for themselves after hatching. Sometimes, the newborn animals may even face danger from their own parents, who may attack and eat them! Even when the newborn animals receive care from their parents, it is normally from the mother, who may have incubated them and takes care of them.

Yet, the situation is reversed in the case of frog native to the forest streams of Argentina and Chile, Rhinoderma darwinii, better known as Darwin’s Frog. Instead of simply fertilizing the eggs laid by the female and leaving, the male Darwin’s Frog goes above and beyond the call of duty, guarding the eggs for 2 weeks before they hatch, and then taking care of the young tadpoles until they mature and are able to fend for themselves. What is unique about the male Darwin’s Frog is the way in which it takes care of its young: by carrying them within its own throat! This creates the misleading illusion that the male Darwin’s Frog is actually “giving birth” from its mouth when the young emerge from the safety of its vocal sac.

But more than simply protecting its young within its own body, evidence has been found that points to the existence of a trophic relationship between the young and the parent: the larvae actually absorb nutrients from the parent frog. In a study conducted in 1986, by inserting several tracer chemicals into the parent frog, such a relationship was deemed possible, as the chemicals inserted were discovered in the bodies of the larvae (O. Goicoechea et al, 1986).

Such parental behavior on the part of the male animal certainly is quite unique within the Animal Kingdom, especially as the Darwin’s Frog not only protects its young but even carries them within itself and lets them absorb its nutrients. It’s no wonder that male Darwin’s Frogs were actually mistaken for viviparous females giving birth when first discovered. Truly a father that is worthy of a gold star!

Sources:

“Darwin’s Frog: video, facts and news” BBC Wildife Finder. URL: “http://www.bbc.co.uk/nature/species/Darwin%27s_Frog”. (accessed 06 April 2010)

“Darwin’s Frog” by ChildCarriers.com. URL: “http://www.childcarriers.com/assets/popups/animals/img/THUMBS/darwinsfrogTB.jpg”. (accessed 07 April 2010.)

Oscar Goicoechea, Orlando Garrido and Boris Jorquera, 1986. Evidence for a Trophic Paternal-Larval Relationship in the Frog Rhinoderma darwinii Journal of Herpetology, Vol. 20, No. 2 (Jun., 1986), pp. 168-178

The grey wolf (Canis lupus), commonly known as wolf, is known to share genetic similarities with the domestic dog (Canis lupus familiaris). While they both share some similar characteristics and genetic material, their physical appearance and behavioral attitudes differ largely.

“Dr. Temple Grandin, animal behavioral geneticist at Colorado State University, claims that domestication is best defined as “a process by which a population of animals becomes adapted to man and the captive environment by some combination of genetic changes occurring over generations” (Grandin & Deesing, 1998) (Miles)

The main reason for the physical and behavioural differences between dogs and wolves would be domestication.

As a dog undergoes domestication when it is young, it stays in the same behavioural state as that of a wolf pup. They are the striking example of the retention of juvenile attributes in grown up dogs. This is known as neoteny. Examples of similar behaviour would be obedience and submissiveness. Not only are their behavioural attitudes similar to wolf pups, their physical outlook also bears more resemblance to the wolf pups than to the grown up wolves.

Domestication also affects different behaviours such as a dog barking and a wolf howling. Barking is commonly seen to be developed through domestication as a warning system to humans. (Miles)

References:

Coppinger R, Feinstein M: ‘Hark! Hark! The dogs do bark…’ and bark and hark. Smithsonian 21:119-128, 1991

Richard Murray and Helen Penridge. Dogs and Cats in the Urban Environment: A Handbook of Municipal Pet Management. Second edition, 2001, ch. 11

Differences Between Wolves and Domestic Dogs. (n.d.). Retrieved March 2010, from In the Company of Wolves: http://www.wolfdog.ws/html/differences.html

Miles, K. (n.d.). Of Wolves & Dogs: Dispelling the Myths. Retrieved March 2010, from Florida Lupine Association, Inc.: http://www.floridalupine.org/publications/PDF/Of_Wolves_and_Dogs–Dispelling_the_Myths.pdf

“Snow Wolf” by Tambako the Jaguar on Flickr, April 2010. URL: http://www.flickr.com/photos/tambako/3315654039/

“Wolf Mix” by Rennett Stowe on Flickr, April 2010. URL: http://www.flickr.com/photos/tomsaint/3117105850/

The grey wolf (Canis lupus), commonly known as wolf, is known to share genetic similarities with the domestic dog (Canis lupus familiaris). While they both share some similar characteristics and genetic material, their physical appearance and behavioral attitudes differ largely.

The main reason for the physical and behavioural differences between dogs and wolves would be domestication.

“Dr. Temple Grandin, animal behavioral geneticist at Colorado State University, claims that domestication is best defined as “a process by which a population of animals becomes adapted to man and the captive environment by some combination of genetic changes occurring over generations” (Grandin & Deesing, 1998).

As a dog undergoes domestication when it is young, it stays in the same behavioural state as that of a wolf pup.

The biological process of domestication resembles natural selection because the parent animals are forced to be reproductively isolated from the wild population.

The small founder group of captive animals is, at first, very inbred; however, in time it will undergo a process of genetic drift, which is an accumulation of random mutations that occur in small populations. Over successive generations, the domesticated animals will also undergo genetic changes in response to their new, human environment (Clutton-Brock, 1995).

Domestication also affects different behaviours such as a dog barking and a wolf howling. Barking is commonly seen to be developed through domestication as a warning system to humans.

Domestication has altered the physical appearance of dogs. Dogs present a striking example of neoteny, the retention of juvenile characteristics in the adults. They are similar to young wolves in many of their mannerisms and physical features, such as large heads, flat faces, large eyes, submissiveness and vocalizing – all of which are exhibited in wolf puppies.