- July 2015
- June 2015
- June 2014
- May 2014
- April 2014
- March 2014
- January 2014
- November 2013
- October 2013
- August 2013
- July 2013
- May 2013
- April 2013
- January 2013
- September 2012
- August 2012
- July 2012
- June 2012
- April 2012
- January 2012
- September 2011
- March 2011
- December 2010
- November 2010
- October 2010
- September 2010
- August 2010
- July 2010
- June 2010
- May 2010
- April 2010
- March 2010
- February 2010
- January 2010
- December 2009
Its #SharkWeek this week this week and while I cook up a new post to commemorate this occasion, lets start off with this picture
Today marks the International Polychaete Day and you can use #InternationalPolychaeteDay on twitter to follow interesting discussions on Polychaetes but while the focus is on Polychaetes, I have a rather interesting flatworm that I will discuss in this post.
Flat worms are of the phylum Platyhelminthes, the main difference between the two groups is that polychaetes are segmented and plathyhelminthes are not. This particular post is about the mating styles of Macrostomum hystrix a hermaphroditic flatworm that quite literally “fucks itself in the head” – yup, you read that right!
Flat worms are capable of self fertilization because they are Hermaphrodites – animals that produce both sperm and eggs and although they do prefer mating with other worms they do have the ability to self fertilize as a back up plan. A very good description of this can be seen in this YouTube video which describes the mating ritual as “penis fencing”.
In a paper just published in the Proceedings of the Royal Society B, a group of scientists studying the mating behavior and adaptations to hypodermic insemination in M. hystrix researched this ability by splitting 100 individuals into two groups, one batch had isolated individuals and the other had animals in small groups (three to a group) and kept them for a month before measuring the sperm living in their bodies. What they found was that isolated flatworms had more sperm in their heads compared to those in groups who had sperm more towards their tail ends leading to the discussion that isolated worms must have self fertilized themselves. While the act of self insemination itself was NEVER observed, the placement of the sperm does suggest a strange insemination route – animals living in isolation must have swung their sharpened penis around to inject themselves in the head.
While lots of animals are able to self fertilize, this is the first example of one that uses a hypodermic appendage to do so.
Ramm Steven A., Schlatter A, Poirier M, Scharer (2015) Hypodermic self-insemination as a reproductive assurance strategy. DOI 10.1098/rspb.2015.0660
I always love a good fighting fish when not fishing off a hand line and I’ve had my share of memorable moments but this next catch that I am going to talk about here is one of the few moments that I will remember not because of the fight in the fish but because
I wont be able to get a bite off this beautiful specimen. In a way, it was a wasted resource, at least not for science anyway.
So a few days after my glorious double wahoo day I was out on the water again with my lines in the water and my eyes into the horizon of this beautiful spot. The day was hot and the sun was out but the cool ocean breeze was just enough to keep us on deck looking out onto the water and waiting for that magical sound from the reels when a fish was on the line. It had been some time since the lures went into the water and everyone was slowly losing focus on the reels and moving about doing their duties for the afternoon. All of a sudden, that famous crunching sound was in the air and the reel was paying out, “fish on!”
It was a good fight and it was worth it when the fish was landed on deck as on the other end of the line was a Great Barracuda (Sphyranea barracuda), an animal that inhabits coastal waters and offshore reefs, feeds on other fishes and is distinguished by faint oblique bars on its back and usually has scattered black blotches on its side. Its a good feed too and reminded me of those days when a barracuda at this time of the day was the perfect excuse for a 6-pack some salad and a front row seat to the sun disappearing in the horizon pulling back its rays like and octopus going back into its crevice.
What was disappointing was that at my feet was a magnificent animal, one of the top predators of the oceans but also one that currently has a ban on eating (link to ban in Australia). Barracuda is a great fish but is also the main carrier of Ciguatera, a neurotoxin that is caused by a dinoflagellate that occurs in algae. When the algae are stressed either by human or natural activities, they react by increasing the amount of this toxin in them. Other herbivorous fishes eat these algae
and ciguatera makes its way into the food chain and eventually into the bodies of these beautiful animals where is accumulates and can then be passed onto humans.
There is currently a ban on eating Barracuda in Australia and I have decided that this one is not going on my dinner plate. On any other day, this would go back to the sea but right now, I will sacrifice this animal for science will be collecting some flesh and liver tissues from this animal for science.
BomaiCruz will be spending a lot of time this year out on oceanic cruises. Internet accessibility might not be great on most of these cruises but I will do my best to keep you all posted in this short time out. For starters, here is a taste of what my day is usually like.
I am currently working with a team of scientists doing environmental studies around selected sites. I am not able to disclose information on the study sites just yet but I can tell you a little bit about what we are doing.
For this leg of the cruise, we are doing a near shore coral reef and fish survey. Our targets are locations close to human settlement so we can get an idea of the impacts of humans on these reefs and the fish life there. To be brief, I can say that what we are seeing is not good.
Anyways, that aside, my day was spent diving, bottom fishing and some trawling. Caught some fish but the highlight of my day was the two Wahoos (Acanthocybium solandri) pictured here. What a day it has been…
Below is a picture taken from a mobile phone at 7 am, Thursday, 26th June, 2014. According tot he person who took the picture, the glow seemed to have a tail, was very bright and was stationary in the sky (well if it was moving, it was very slow).
The descriptions provieded so far tend to point to a comet. While internet searches does indicate that 5 commets will be passing by earth this month (June), none of these would be visible without a telescope. So what exactly could this unexplained light be?
While discussing the Reptiles of Papua New Guinea, Rom and Zai Whitaker (1984) have done very little to talk about sea turtles eventhough their fresh water cousins are widely represented. In my discussions of the Reptiles of Papua New Guinea, I will go out of my way to provide some information on the sea turtles of Papua New Guinea. All information provided for sea turtles are readilly available on the net, I will only attempt to capture the relevant information and provide links for further readings.
Rom and Zai Whitaker (1984) have done very little to talk about sea turtles
Flatback sea turtles (Natator depressus) get their name from their flat carapace or shell, which is unlike the curved shell of other turtle species. The carapace on flatbacks are greyish-green in color with the outer margins distinctly upturned. Other distinguishable features include a single pair of prefrontal scales at teh front of the head and four pairs of coastal scutes on the carapace.
Flatbacks have the smallest distribution of all sea turtle species and only breeds and nests in Australia although their distribution range can span tot eh southern part of Indonesia and Papua New Guinea. Flatbacks are also small in size, reaching up to 1 m in length and weighing up to 90 kg.
Flatbacks are omnivores, feeding on a variety of prey including sea cucumbers, jellies, soft corals, shrimps, crabs, molluscs, fish and seaweed.
Current status can not be classified internationally because of their restricted range, however, in Australia, flatback turtles are listed as Vulnerable under the Australian Commonwealth’s Endangered Species Protection Act. The main threats to this species include;
- habitat loss and degradation
- wildlife trade
- collection of eggs and meat for consumption
- incidential catch (bycatch)
- climate change and
Flatbacks are also threatened by predation by other animals including foxes, feral dogs and pigs. Despite their limited range and non-migratory behaviour, this species remains the least studied sea turtle species.
Links and resources
Papua New Guinea (PNG) is home to six of the worlds seven sea turtle species of which all but the flatback turtle come ashore to nest. Sea turtles have always been part of PNG culture providing meat, eggs and ornaments that hold special places in the PNG culture but would these animals be here forever?
15,120 turtles are killed in PNG each year
Right now all seven sea turtle species are endangered. A study released by the United Kingdoms University of Exeter showed that approximately 42,000 sea turtles are killed worldwide every year and PNG contributes more that 36 percent of this figure, thats a whooping 15,120 turtle deaths each year.
Where the harvest of sea turtles was once for “home use” only, this practice is now being expoilted for money.
Sea turtles that migrate through the waters of PNG include the Loggerhead, Flatback, Green, Hawksbill, Pacific Ridley and Leatherback turtles. All but the Flatback come ashore to nest. Turtle nesting season in PNG is usually between the months of November through January.
Loggerhead turtles (Caretta caretta)are the second largest hardshelled turtle species and can grow up to 95 cm in length, reaching weights up to 200 kg although the heaviest one tipped the scales at 545 kg. Loggerheads can be identified by their yelow-orange to reddish-brown carapiece and pale yellow plastron (underside). Loggerheads also have five vertebral scutes rinning down the turtles midline bordered by fove pairs of coastal scutes.
Next week: Flatback turtles
Rom and Zai Whitalker (1982) Reptiles of Papua New Guinea
After the New Guinea Crocodile (Crocodylus novaeguineae), the saltwater crocodile (Crocodylus porosus) is the only other crocodylian species found in Papua New Guinea (PNG). C.porosus has a wide distribution ranging from the Solomon Islands to Sri Lanka and India and is the largest of all the worlds crocodiles, growing up to more than 6 m (20 ft) long and weighing over a tonne (2,300 lbs).
Saltwater crocodiles share lowland river and swamps with freshwater crocodiles and are more common closer to the coast. In New Guinea and in particular, PNG, they can be found on all the island provinces and have been known to inhabit crater lakes too. Their typical habitat is mangrove and coastal swamps and roundwaters and despite their name, are quite at home in freshwater too.
Like their cousins, the New Guinea crocodile, saltwater corcodiles make mound nests from vegetation, guard their nests from predators and release their yound from the mounds at hatching time. In the Sepik, saltwater corcodiles tend to nest between the months of April and June and often ues the same nests as the New Guinea crocodile although by this time all eggs of the New Guinea crocodile would have been hatched and gone already. For populations on the southern side of PNG, nest time is between November and Jamuary although some can nest as early as September or as late as March.
The feeding habits of saltwater crocodilesa re similar to those of the freshwater crocodile, with the exception that they will take much larger prey more often and occassionally kill humans. Outside of PNG, saltwater crocodiles have been hunted to near extermination for its valuable skin but PNG and northern Australia still harbour safe breeding populations for this species and represent the last strongholds of this great reptile.
Rom and Zai Whitaker, (1984) Reptiles of Papua New Guinea
I know of the existance of clans outside of the Sepik that have different animals including crocodiles as their totem but a part from the Sepiks, this is the first time I have seen a reference made to people outside the Sepik, in particular, the Manus people
In discussing the Reptiles of Papua New Guinea (PNG), it is only fitting that we start with crocodiles who not only are at the top of the food chains in their local habitats but also hold important roles in art and tradition and form the basis of a major skin industry that is also a means of sustenace to many river dwelling people. Crocodile meat is also eaten by many people but notably not by members of the crocodile clans like some in Manus (this is facinating to me since, I know of the existance of clans outside of the Sepik that have different animals including crocodiles as their totem but a part from the Sepiks, this is the first time I have seen a reference made to people outside the Sepik, in particular, the Manus people).
New Guinea Crocodiles grow up to 3.6 m (12 feet) though there have beed unverified claims of 14-footers being sighted. They can easily be identified by the presence of prominent, pointed post-occipital scales on the top of the neck just behind the head. These scales are absent in salt water crocodiles. New Guinea crocodiles inhabit swamps, rivers, lakes, roundwaters and streams throughout the lowlands of the main island of New Guinea and are not recorded in any of the major islands.
Rom and Zai Whitaker, (1982) claim that females reach maturity when they are about seven years old, measuring between 2 and 2.5 meters long, however, current records show that female maturity can come much earlier when the animals are between 1.6 and 2 m long. Nesting season is around the same months, usually between August and January but because of the terrain, these months can mean a drier season for the northern population and a much wetter one for southern populations of this species.
New Guinea Crocodiles have a range in body colour from grey to brown with darker bandings on the tail and body which becomes less noticeable as the animal grows. Snouts are long and pointy when young and becomes wider as the animal matures.
Rom and Zai Whitaker, (1982). Reptiles of Papua New Guinea