LSM1303 Animal Behaviour

The Kiwa hirsutra dubbed as the Yeti Crab of the Pacific

Yeti of the Pacific? Check out the furry resemblance!

“Marine biologists have discovered a crustacean in the South Pacific that resembles a lobster or crab covered in what looks like silky fur” (BBCNews, 2006). This animal is a unique discovery and a new taxonomic family has been created just for it. It now belongs to the newly named family called “Kiwaida”, named after the goddess of crustaceans in Polynesian mythology. It is white and 15 cm long, according to Michel Segonzac of the French Research Institute for Exploitation of the Sea.

The special feature of this animal is its furry pincers. The Kiwa hirsutra is said to habitate in some Pacific deep sea hydrothermal vents, which spew out fluids that are toxic to many animals. The furry pincers also contain lots of filamentous bacteria, which could either be used to “detoxify poisonous minerals from the water, allowing it (K. hirsuta) to survive around the vents” (BBCNews, 2006) or serve as food for the animal. 

This special feature could possibly a result of evolution, to allow the animal to survive in harsh conditions like the hydrothermal vents. A detailed study of this animal could be found in the journal article “A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacfic-Antarctic Ridge” (Macpherson et. al, 2005).

Citations:

“Furry lobster found in Pacific,” by BBCNews, 8 Mar 2006

“A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacfic-Antarctic Ridge” by Macpherson et. al, 2005, Zoosystema 27(4): 709-724

When I watched The Lion King many years back, I was always intrigued by the trio of hyenas, Shenzi, Banzai and Ed. It was less the fact that they were depicted to be villainous and treacherous. Rather, I was more intrigued by the group dynamics of the hyenas which consisted of two males led by a female (Shenzi). Was the portrayal mere fiction, or did it depict real group behaviour in the wild life? More significantly, how is the alpha (fe)male selected?

Spotted hyenas live in a clan, which is led under a matriarch and a series of hyenas below her. These include multiple unrelated adult males and multiple matrilineal kin groups of related females and their young. The clan can consist of up to 90 individuals (Holekamp, n.d.). The sheer size of the clan implies that there is strong competition not only for resources, reproduction rate and survival, but also to be the dominant female. In this regard, the social status of a female hyena is determined by her mother’s social rank, and not by her size or aggressiveness. In other words, the social status is inherited from the mother.

Even if social status is inherited, there is a great deal of social learning involved by the juvenile female hyena. This involves recognising group members which they can dominate. In this instance, the mother helps the juvenile win contests against the females which are already subordinate to the mother (Science Daily, 2009). Once the juvenile reaches adulthood, she needs only to maintain the status that has been set by with the aid of the mother. This disproves an alternative hypothesis that posits that mothers might transfer genes that cause their offspring to be as competitive as themselves. This is because as mentioned earlier, there is social learning during the juvenile period.  
Hyenas prefer as social companions individuals who are higher ranking but close to themselves in rank, and subordinate individuals usually initiate these associations (Holekamp, n.d.). In other words, hyenas recognise that some members are more valuable than others. There is a pragmatic side to this of course. It is for survival. Breeding males prefer to associate and mate with high- over low-ranking females because cubs of higher-ranking females survive so much better than do those of low-ranking females. Access to resources for example, depends on the ranking of the hyena (ibid). This proves that the ranking of the mother matters in determining the future rank of the hyenas born.

To end, I guess it appears to be cruel to that social status of the mother plays a dominant role in determining the survival of the young hyenas. Yet then again, survival of the fittest prevails.

References:

http://www.life-of-science.net/zoology-and-botany/news/hyenas-actively-pass-their-social-state-on-to-their-offspring.html

http://www.sciencedaily.com/releases/2009/02/090225073209.htm

http://www.cell.com/current-biology/fulltext/S0960-9822(06)02316-5

Mother and offspring

The importance of mothers, or high-ranked female hyenas, extends towards mating too.

The humble dung beetle , destined for a lifetime of shit has now expanded its diet to include chomping on live millipedes!

Scientists from Peru have recently discovered a particular species of dung beetle (Coleoptera: Scarabaeidae), Deltochilum valgum, which is the first of its kind to display predatory behaviour, using its modified head and sharper “teeth” to decapitate live millipedes and slice up ther rest of the body for feeding.

Using infrared cameras, the research team led by Dr. Trond Larsen were able to catch live footage of the nocturnal dung beetles in action. Dung beetle heads are normally flat and shovel-like, useful for burrowing in a dung pile. However, D. valgum has a much narrower and pointy head, adapted to get inside the millipede’s body and feed on its insides. The sharper ‘teeth’ they posses are also useful in severing the head of the millipedeand cutting up the body into smaller pieces.

Talk about ferocious!

watch?v=VjLfcHTwr6E
Supplementary material video accompanying Biology Letters article ‘From coprophagy to predation: a dung beetle that kills millipedes’.
Such behaviour intrigues scientists as there is a huge jump from coprophagy (dung feeding) to carnivory. They hypothesise that this unusual evolutionary transition was driven by the high levels competition for food.

This extraordinary behaviour of carnivorous dung beetles is certainly one which will change the way we view the humble dung beetle!
For more information:

Larsen, T., Lopera, A., Forsyth, A. & Genier, F. 2009. From coprophagy to predation: a dung beetle that kills millipedes. Biol. Lett. 5 : 152-155

BBC News “Little dung beetle is big chopper”. Accessed 8th April 2009. (http://news.bbc.co.uk/2/hi/science/nature/7840404.stm)