Leafy Sea Dragons

Endemic to the waters of Southern Australia, Leafy sea dragons (Phycodurus eques) belong to the Syngnathidae family (which includes seahorses, pipefish, and weedy seadragons, Phyllopteryx taeniolatus, the leafy sea dragons closest relative). These majestic creatures have leaf like appendages (hence the name), which aid in camouflage, and grow up to 43cm in length (Larson et al. 2014).

A leafy sea dragon pictured in the wild (Photograph by George Grall)

Unlike their reddish coloured cousins (weedy sea dragons), leafy sea dragons are typically yellow with olive-brown specked appendages. This colouration helps the sea dragon to blend into the kelp and seaweed formations they live amongst (Larson et al. 2014).

Though they do maintain sanctuary hidden amongst the underwater forests, leafy sea dragons do have a defence mechanism in the form of long spines located on the side of their bodies. Leafy sea dragons are incredibly vulnerable to population disruption with ever-increasing pollution and habitat degradation, as well as harvesting for aquariums, low genetic diversity and dispersal, and small home ranges unfortunately leading to population fragmentation (Larson et al. 2014).

Watch the video below to see the leafy sea dragon floating majestically amongst aquatic vegetation.

WATCH: Leafy Sea Dragon, South Australia - Phycodurus eques 

 

References:

Larson, S., Ramsey, C., Tinnemore, D. & Amemiya, C. 2014, "Novel Microsatellite Loci Variation and Population Genetics within Leafy Seadragons, Phycodurus eques", Diversity, vol. 6, no. 1, pp. 33-42.

National Geographic, 2015. “Leafy and Weedy Sea Dragon (Phycodurus eques, Phyllopteryx taeniolatus)”. Accessed 19^th May 2015 http://animals.nationalgeographic.com.au/animals/fish/sea-dragon/

Leaf Fish

In the animal world, its kill or be killed. Many animals develop weaponry or aggressive behaviour to defend them selves against predators. But not the leaf fish!

Leaf fish are a diverse group found in Asia (Nandidae), South America (Polycentridae) and Africa (Polycentropsis abbreviata; Barlow, 1967; Catarino & Zuanon, 2010).

In this weeks blog post I will focus on the South American species observed in and around the Amazon basin.

WATCH: Build for The Kill – Leaf Fish

These amazingly deceptive fish camouflage themselves into streams, lakes and rivers by mimicking leaves. With a laterally compressed body shape, mottled patterns and colours, leaf fish remain hidden from predators. Their camouflage efforts even go as far as forming an extended filament in the lower jaw to resemble a petiole (a must-have for any leaf related costume). Seemingly harmless, the fish can go completely undetected by prey until they strike with their large protractile mouths (Barlow, 1967; Catarino & Zuanon, 2010).

References:

Barlow, G.W. 1967, "Social Behavior of a South American Leaf Fish, Polycentrus schomburgkii, with an Account of Recurring Pseudofemale Behavior", American Midland Naturalist, vol. 78, no. 1, pp. 215-234.

Catarino, M.F. & Zuanon, J. 2010, "Feeding ecology of the leaf fish Monocirrhus polyacanthus (Perciformes: Polycentridae) in a terra firme stream in the Brazilian Amazon", Neotropical Ichthyology, vol. 8, no. 1, pp. 183-186.

Leaf Insects

I’m not going to talk about how a leaf insect mimics a leaf, that would be too obvious! Instead I’m going to discuss the nature in which Spiny Leaf insects (Extatosoma tiaratum) lay their eggs and deceive ants in the process. 

A female adult spiny leaf insect (Extatosoma tiaratum) displayed on a leaf (AUSECO, 2008)

Eggs produced by leaf insects resemble seeds often from a mixture of toxic and non-toxic plants (eg. Lupins sp. and legumes respectively). A capitula like structure formed on the crown of the egg is lipid rich and a favourite food of ants. The ants carry the egg to their nests where it is protected from birds and other predators such as wasps. Once the egg has hatched, the first instar nymph stage resembles the larvae of ants (documented in Leptomyrmex ants by Key, 1970) facilitating movement from the nest to the surface without detection. This deception allows for increased survival of leaf insects eggs, where on the surface they would have been predated by birds. Shelomi (2011) found that quails (Coturnix japonica) and chickens (Gallus gallus domestica) eagerly consume the eggs produced by spiny leaf insects, but unlike most plant seeds the eggs did not survive digestion. Just one in nearly a thousand eggs remained intact after consumption by these bird species, providing strong observations that without the protection by ants in their nests spiny leaf insect eggs would not survive long enough to hatch, detrimental to the population of the species (Key, 1970; Sellick, 1997; Shelomi, 2011).

WATCH: the interaction between ants and spiny leaf insect eggs as shown by David Attenborough 

References:

Key, J. 1970. “Phasmatodea”, CsiRo (ed.) the insects of Australia. Melbourne University Press, Melbourne, Australia pp. 348-359

Sellick, J. 1997, "The range of egg capsule morphology within the phasmatodea and its relevance to the taxonomy of the order", Italian Journal of Zoology, vol. 64, no. 1, pp. 97-104.

Shelomi, M. 2011, "Phasmid Eggs Do Not Survive Digestion by Quails and Chickens", Journal of Orthoptera Research, vol. 20, no. 2, pp. 159-162.

Image:  

AUSECO, 2008.  http://www.auseco.com.au/index.asp?pagename=eco+updates+phasmids

Accessed: 10th May 2015