Hunting and Feeding: Giraffe (Giraffa camelopardalis)

The extremely long neck associated with the giraffe is a very beneficial evolutionary adaptation that allows this large animal to compete with many smaller herbivores that inhabit the African Savannah (Pellew, 2009). Due to their intense height, giraffe’s are able to reach well above their competitors and selectively browse the best parts of the tallest trees, feeding primarily on fruits, flowers and fresh shoots on 40 – 60 different species including commiphora, mimosa and even spiny acacia (Uhlenbroek, 2008).

Giraffes possess the ability to nip leaves from between the long thorns of acacia trees due to the presence of long muzzles, flexible lips and a long, dextrous tongue which enables them to reach deeps into clumps of tree branches (Dagg & Foster, 1976). Because their lips and tongue are covered with thick, horny bumps called papillae, giraffes are seemingly immune to the acacias thorns (Dagg & Foster, 1976).

To ensure they have access to sufficient quality and quantity of food – with adults eating up to 35kg a day – the giraffe roams widely and in lean times can consume dried leaves, twigs and even thorns (Uhlenbroek, 2008). Giraffes are ruminants, meaning they possess four stomachs and first chew and swallow their food, before regurgitating and re-chewing, a process that happens several times before digestion is complete (Pellew, 2009).  Uniquely however, the giraffe is able to ruminate while walking, an adaptation which is perfect for their roaming, nomadic lifestyle (Uhlenbroek, 2008).

Reference:

Dagg, A.I. & Foster, J.B. (1976). The giraffe: It’s biology, behaviour and ecology. Van Nostrand Reinhold Co., NY.

Pellew, R.A. (2009). The feeding ecology of a selective browser, the giraffe (Giraffa camelopardalis). Journal of Zoology, 202(1), 57-81.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.

Hunting and Feeding: Alligator Snapping Turtle (Macroclemys temminckii)

The Alligator snapping turtle is a master of disguise; blending seamlessly with the rocks and debris of its river based home it is the ultimate ambush predator (Bowen et al, 2001). This turtle gets its name from the crude but effective method of hunting mainly due to the way it sits with its mouth open like a crocodile or alligator in the sun, then snaps its jaws shut is a swift movement (Pritchard, P.C.H, 1989). These unusual turtles inhabit the lake and river ecosystems of North America and can grow up to 65cm long (Uhlenbroek, 2008).

Because the snapping turtles entire body – including the inside of its mouth and eyes – are the same drab colour and pattern, the long, wiggly, red tongue is the only distinguishing feature that can be seen by prey and resembles perfectly the movement of a worm (Bowen et al, 2001). As such the turtle simply lies in wait, with its hooked jaws held wide open, and wiggles its tongue around in an attempt to mimic the movement of a worm to attract prey (Uhlenbroek, 2008).

Once prey comes close enough, the turtle quickly snaps its hard jaws shut, crushing the prey instantly before swallowing (Pritchard, P.C.H, 1989). The snapping turtles diet consists mainly of fish, snakes and amphibians but they are also know to prey on other turtles or even readily eat carrion if the opportunity arises (Uhlenbroek, 2008).

References:

Bowen, B.W., Moler, P.E., Roman, J. & Santhuff, S.D. (2001). Population Structure and Cryptic Evolutionary Units in the Alligator Snapping Turtle. Conservation Biology, 13(1), 135-142.

Pritchard, P.C.H. (1989). The alligator snapping turtle: Biology and conservation. Milwaukee Public Museum, WI.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.

Hunting and Feeding: Box Jellyfish (Chironex fleckeri)

The notorious box jellyfish, Chironex fleckeri, is not only among the world’s most dangerous venomous creatures, it is also a very active and formidable predator (Alderslade et al, 1998). The box jellyfish uses the venom in its tentacles not just as a defence mechanism, but also for the express purpose of incapacitating and eating its prey (Marsh and Slack-Smith, 2010). Equipped with as many as 15 tentacles, lined with thousands of stinging cells and armed with over 5,000 specialized barbed nematocysts per arm, the sting from a box jellyfish has the ability to pierce flesh, crustacean cuticle and even the shells of molluscs (Uhlenbroek, 2008). Each cell contains a filament lined with barbs that, when triggered by contact with prey, release explosively and instantly stun and paralyse the target (Marsh and Slack-Smith, 2010). The rapid ejection of this barb is one of the fastest cellular processes ever recorded in nature and turns the barbed filaments inside out with roughly the same energy as firing a small-calibre bullet (Uhlenbroek, 2008).

Belonging to the class Cubozoa, box jellyfish are not true jellyfish but are closely related (Marsh and Slack-Smith, 2010). They are capable of moving at speeds up to 7.2kph by using a form of jet propulsion and are equipped with 24 eyes arranged in four groups of six on each side of the body (Marsh and Slack-Smith, 2010). While most of these eyes are simple organs capable of responding only to light and dark, one pair in each cluster has the ability to form images and may guide the jellyfish to its prey (Uhlenbroek, 2008).

Whilst the box jellyfish usually preys on small fish and crustaceans, they pose a significant threat to humans with its excruciatingly painful stings causing heart failure and shock often leading to drowning (Uhlenbroek, 2008).

Reference:

Alderslade, P., Bloom, D.A. & Burnett, J.W. (1998). Partial purification of box jellyfish (Chironex fleckeri) nematocyst venom isolated at the beachside. Toxicon, 36(8), 1075-1085.

Marsh, L.M. & Slack-Smith, S. (2010). Field Guide to Sea Stingers and Other Venomous and Poisonous Marine Invertebrates. Western Australia, AUS: Western Australian Museum.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.

Hunting and Feeding: Red Crossbill (Loxia curvirostra)

The red, or common, crossbill is a species of finch whose diet consists almost exclusively on the seeds of coniferous trees (Hahn, 1998). As such they have adapted a distinctive trait that enables them to deal with their specific diet. The unusual crossed bill of these birds allows them to prise open the tough cones of conifers before they ripen and open naturally (Uhlenbroek, 2008, pg 191). Their adapted bill comprises of an elongated upper bill and a shorter, crossed lower bill, which – while common to all crossbill species – can differ in size and shape between species and populations within a species according to their preferred type of cone, be it spruce, pine or larch (Marquiss, 2002).

In order to feed, the crossbill simply inserts its closed bill into a cone and opens the crossed tips, thereby prising open the scale of the cone and allowing the bird to eat the seed inside (Marquiss, 2002). Because of their highly resinous diet, these birds must frequently visit water sources in order to drink and clean off their bills (Uhlenbroek, 2008, pg 191).

The adaptation of this bill gives an advantage over other finches inhabiting the same area due to the ability of the common crossbill to breed whenever the cone crop ripens, even during the winter months (Hahn, 1998).

References:

Hahn, T.P. (1998). Reproductive seasonality in an opportunistic breeder, The Red Crossbill, Loxia curvirostra. Ecological Society of America, 79(7), 2365-2375.

Marquiss, M. & Rae, R. (2002). Ecological differentiation in relation to bill size amongst sympatric, genetically undifferentiated crossbills Loxia spp. International Journal of Avian Science, 144(3), 494-508.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.

Hunting and Feeding

Feeding is fundamental in providing plants and animals with the energy required to undertake various chemical processes within their bodies that are essential for life (Uhlenbroek, 2008, pg 179). There is a wide variety between animals in regards to the food they eat and how it is obtained; from carnivorous bears to herbivorous deer. To achieve this, a range of adaptations have evolved.

Animals are generally classified according to their diet; carnivores eat other animals and so have developed specialized detection methods and behaviours such as stalking, ambushing and co-operating with one another to bring down larger prey (Uhlenbroek, 2008, pg 179).

Herbivorous diets consist of plants and as such they have also formed specialized behaviours that allow them to feed. The evolution of grinding teeth – such as in elephants – allow them to chew tough plants and unique inner organs such as the appendix in koalas allow a diet of entirely eucalyptus leaves (Bollinger et al, 2009).

Omnivores and scavengers feed on a wide variety of food including plants, animals and decaying matter (Clark, 1982). Consequently, they often lack any highly specialized adaptation but instead require the flexibility to utilise such a wide range of food (Uhlenbroek, 2008, pg 179).

These different types of feeding behaviours and adaptations allow for the development of food webs within ecosystems.

References:

Clark, D.A. (1982). Foraging Behavior of a Vertebrate Omnivore (Rattus Rattus): Meal Structure, Sampling, and Diet Breadth. ESA Ecology, 63(3), 763-772.

Bollinger, R.R., Everett, M.L., Fisher, R.E., Parker, W., Smith, H.F.& Thomas, A.D. (2009). Comparative anatomy and phylogenetic distribution of the mammalian cecal appendix. Journal of Evolutionary Biology, 22(10), 1984-1999.

Uhlenbroek, C. (2008). Animal Life. Penguin Group, UK.