Indo-pacific bottlenose dolphin

Indo-Pacific Bottlenose dolphin

The Indo-Pacific bottlenose dolphin is a species of Bottlenose dolphin. This dolphin grows to 2.6 m long, and weighs up to 230 kg . It lives in the waters around northern Australia , South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its underside is lighter grey or nearly white with grey spots. The Indo-Pacific bottlenose dolphin is usually smaller than the Common bottlenose dolphin, has a proportionately longer Rostrum, and has spots on its belly and lower sides. It also has more teeth than the common bottlenose dolphin ‚ÄĒ 23 to 29 teeth on each side of each jaw compared to 21 to 24 for the common bottlenose dolphin.

Much of the old scientific data in the field combine data about the Indo-Pacific bottlenose dolphin and the common bottlenose dolphin into a single group, making it effectively useless in determining the structural differences between the two species. The IUCN lists the Indo-Pacific bottlenose dolphin as “near threatened” in their Red List of endangered species.

Until 1998, all bottlenose dolphins were considered members of the single species Tursiops truncatus. In that year, the Indo-Pacific bottlenose dolphin was recognized as a separate species. Both species are thought to have split during the mid-Pleistocene, about 1 million years ago. Some evidence shows the Indo-Pacific bottlenose dolphin may actually be more closely related to certain dolphin species in the Delphinus (genus), especially the “Atlantic spotted dolphin”, than it is to the common bottlenose dolphin. However, more recent studies indicate that this is a consequence of reticulate evolution (such as past hybridization between Stenella and ancestral Tursiops and incomplete lineage sorting, and thus support truncatus and T. aduncus belonging to the same genus. Burrunan dolphin T. (aduncus) australis has been alternately considered its own species, a subspecies of T. truncatus, or a subspecies of T. aduncus. Following the results of a 2020 study, the American Society of Mammologists presently classifies it as a subspecies of T. aduncus. The same study delineated 3 distinct lineages within T. aduncus which could each be their own subspecies: an Indian Ocean lineage, an Australasian lineage, and the Burrunan dolphin. The Society for Marine Mammalogy does not recognize the Burrunan dolphin as a distinct species or subspecies, citing the need for further research. Indo-Pacific bottlenose dolphins are very similar to common bottlenose dolphins in appearance. Common bottlenose dolphins have a reasonably strong body, moderate-length beak, and tall, curved dorsal fins; whereas Indo-Pacific bottlenose dolphins have a more slender body build and their beak is longer and more slender. 

Indo-Pacific bottlenose dolphins feed on a wide variety of fish Cephalopod, Squid, researchers looked at the feeding ecology of Indo-Pacific bottlenose dolphins by analysing the stomach contents of ones that got caught in the gillnet fisheries off Zanzibar, Tanzania.  Indo-Pacific bottlenose dolphins live in groups that can number in the hundreds, but groups of five to 15 dolphins are most common. 

In some parts of their range, they spend time with the common bottlenose dolphin and other dolphin species, such as the humpback dolphin. The peak mating and calving seasons are in the spring and summer, although mating and calving occur throughout the year in some regions. Gestation period is about 12 months. Calves are between 0.84 and 1.5 Meters, and weigh between 9 and 21kg. The calves are weaned between 1.5 and 2.0 years, but can remain with their mothers for up to 5 years, some mothers will give birth again, shortly before the 5 years are up. 

In some parts of its range, this dolphin is subject to predation by sharks. 

Its lifespan is more than 40 years. Indo-Pacific bottlenose dolphins located in Shark Bay, Australia, have been observed using sponges as tools in a practice called “sponging”. A dolphin breaks a marine sponge off the sea floor and wears it over its rostrum, apparently to probe substrates for fish, possibly as a tool. Spontaneous ejaculation in an aquatic mammal was recorded in a wild Indo-Pacific bottlenose dolphin near Mikura Island, Japan, in 2012. Indo-Pacific bottlenose dolphins have been observed to swim near and rub themselves against specific types of corals and sponges. A team of scientists followed up on this behaviour and discovered metabolites with antibacterial, antioxidative, and hormonal activities in the corals and sponges, suggesting that they might be used by the dolphins to treat skin infections. its near-shore distribution, though, makes it vulnerable to environmental degradation, direct exploitation, and problems associated with local fisheries. 

The major predators of this species are typically sharks, and may include humans, killer whales, and sting rays. In the early 1980s, many were deliberately killed in a Taiwanese driftnet fishery in the Arafura Sea, off north western Australia. Large-mesh nets set to protect bathers from sharks in South Africa and Australia have also resulted in a substantial number of deaths. Gillnets are also having an impact, and are a problem throughout most of the species’ range.

These small cetaceans are commonly found in captivity, causing conservation concerns, including the effects of removing the animals from their wild populations, survival of cetaceans during capture and transport and while in captivity, and the risks to wild populations and ecosystems of accidentally introducing alien species and spreading epizootic diseases, especially when animals have been transported over long distances and are held in sea pens.

Bottlenose dolphins are the most common captive cetaceans on a global scale. Prior to 1980, more than 1,500 bottlenose dolphins were collected from the United States, Mexico, and the Bahamas, and more than 550 common and 60 Indo-Pacific bottlenose dolphins were brought into captivity in Japan. By the late 1980s, the United States stopped collecting bottlenose dolphins and the number of captive-born animals in North American aquaria has increased from only 6% in 1976 to about 44% in 1996. South Korea, in the 2010s, environmental groups and animal protection groups led a campaign ko:2013 to release southern bottlenose dolphins illegally captured by fishermen and trapped in Jeju Island.

In a study on three populations of Indo-Pacific bottlenose dolphins in Japan, the characteristics of acoustic signals are believed to be affected by the acoustic environments among habitats, and geographical variation in animal acoustic signals can result from differences in acoustic environments; therefore, the characteristics of the ambient noise in the dolphins’ habitats and the whistles produced were compared. Ambient noise was recorded using a hydrophone located 10 m below the surface and whistles were recorded by using an underwater video system. The results showed dolphins produced whistles at varying frequencies with greater modulations when in habitats with less ambient noise, whereas habitats with greater ambient noise seem to cause dolphins to produce whistles of lower frequencies and fewer frequency modulations. Examination of the results suggest communication signals are adaptive and are selected to avoid the masking of signals and the decrease of higher-frequency signals. They concluded ambient noise has the potential to drive the variation in whistles of Indo-Pacific bottlenose dolphin populations.

Small, motorized vessels have increased as a source of anthropogenic noise due to the rise in popularity of wildlife viewing such as whale watching. Another study showed powerboat approaches within 100 m altered the dolphin surface behaviour from traveling to milling, and changed their direction to travel away from the powerboat. When the powerboat left the area and its noise ceased, the dolphins returned to their preceding behaviour in the original direction.

In Shark Bay, Western Australia, on dolphin behavioural responses showed significant changes in the behaviour of targeted dolphins were found when compared with their behaviour before and after approaches by small watercraft. Dolphins in the low-traffic site showed a stronger and longer-lasting response than dolphins in the high-traffic site. These results are believed to show habituation of the dolphins to the vessels in a region of long-term vessel traffic. However, when compared to other studies in the same area, moderated responses, rather, were suggested to be because those individuals sensitive to vessel disturbance left the region before their study began. Although these studies do show statistical significance for the effects of whale-watching boats on behaviour, what these results mean for long-term population viability is not known. The Shark Bay population has been forecast to be relatively stable with little variation in mortality over time. The Indo-Pacific bottlenose dolphin populations of the Arafura and the Timor Sea are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals “Bonn Convention”. They are listed on Appendix II as they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The Indo-Pacific bottlenose dolphin is also covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region Adelaide Dolphin Sanctuary “Marine protected area”  in the Australian state of South Australia Gulf St Vincent, which was established in 2005 for the protection of a resident population of Indo-Pacific bottlenose dolphins.

When we have links for viewing these species, they will appear below video and the news section

Whales, Dolphins and Porpoises family tree

Cetaceans -Whales, porpoise and dolphins

Few people can avoid stopping to watch, if they spot cetaceans from a cliff. While the family is wide and varied, they are all pretty interesting. From some of the largest and most intelligent hunters such as killer whales to the largest animal on earth the blue whale.

Whale and dolphin watching tourism is worth a lot of money Рthis can be essential, as in many places the extra money helps a community survive. 

I hope, overtime, to make this section of the website as large a list of places to view cetaceans and people who will help you in that quest.

As might perhaps be suspected, all of the mammal species which have returned permanently to the sea, and developed breathing holes located on their back (and therefore perfectly placed for taking quick breaths) are  related.

So what is the most closely related living land mammal? Perhaps obviously, it is a species which spends much time in the water – the hippopotamus.

As with all of these pages, as we create pages for each individual species, they will be linked to the photo below.

So the baleen whales are split into three families, these are not large as there are only 16 species of baleen whales in the world. At the current time, there are roughly 1.1 million baleen whales in the worlds oceans

Below is a family tree of the group

 

Baleen Whales

Baleenideae – the rhight whales

 

The first  living split is Baleenidae, this family is not huge. The north atlantic and north pacific are closest related, these species are closely related to the Southern pacific right whales. Their name is unfortunate Рit is called right whale for 3 reasons, it swims slowly, floats when dead and carries a large amount of oil. This lead to all these species being hunted close to extinction.

The other family is called Balaenopteroidea. Here species peel off slowly. I will list them in the order that they split.

The first split is the minke whale Рof which there are 2 species, the common and southern minke whale, with the grey whale being the next most similar.

The next are the humpback whale and the fin whale followed by the Blue whale.

The last group of whales are from a group called the Brydes whales complex

This completes the list of baleen whales. The other branch of the Cetaceans is known as the toothed whales

Toothed Whale

.I am going to look at them in 3 groups, though the third is not particularly closely related to each other

  • Delphinoidea: This includes
    • Monodontidaes – Belugas and narwhals
    • Phocoenidae – The family of Porpoises (7 species) such as harbour porpoises and Vanquita

 

    • Delphininidae – these are the oceanic dolphins – 37 species split into several subfamilies which we will deal with one by one.
Subfamily Delphininae – 15 species (tamanend bottle nose dolphin only recognized as separate species, will build page for it at some point when photos are readily available.

Subfamily  Globcephalinae 11 species

Subfamily incerta sedis (latin for “of uncertain placement” )6 species

Subfamily Lissodelphininae 6 sppecies

Subfamily Orcininae

  • Inioidea : This includes 3 groups
    • Iniidae (only 1 of 5 genus remains -Inea (4 species: Araguaian river dolphin, Bolivian river dolphin¬† and Orinoco dolphin)
    • Lipotidae: which contains only one species: the Baiji or Chinese river dolphin
  • Pontoporiidae: which contains one species¬†

The next family is the beaked whales. There are 24 species, of which only 3-4 have been well studied. This is because they spend much of their time deep in the sea, it appears that each species does not have many members and they are incredibly reclusive in their habits.

One might ask how an air breathing animal can spend so much of its time deep in the ocean? Well the Curved beaked whale has had a dive timed at 138 minutes. More incredible, they only need around 2 minutes to catch their breathe before sinking back into the depths. This means that if required, they can spend just 20 minutes out of 24 hours at the surface – an incredible stunt.

There appear to be a great number of species that are extinct – these we will not list, but will mention each subfamily in passing.

Incertae sedis contains 5 extinct genus, Basal forms include 13 extinct genus

Subfamily Berardiinae contains 3 genus, 2 of which are extinct, but the third contains 3 living species (and one dead) .  

Genus Beradius

 

Next we cover the Bottlenose whales

Northern                                                                                                                     Southern and                                                        Tropical

Subfamily Ziphiinae  contains 5 genus, 3 are extinct, but two have just one species in each

Genus Tasmacetus: Shepherds beaked whale Genus Ziphius: Cuviers beaked whale

Click on the image to see it in full

As you can see from the whale family tree, the sperm whales are separate from the rest. However, they are toothed whales so belong in this section of the page.

The worlds 3 most destructive industries are fossil fuels, farming and fisheries, yet all three are protected by (and subsidized) by governments

Unfortunately these 3 activities appear to be most responsible for collapse or incredible pressure on ecosystems across the globe.

Both fossil fuel extraction and farming have required huge areas to be deforested
Continue reading “The worlds 3 most destructive industries are fossil fuels, farming and fisheries, yet all three are protected by (and subsidized) by governments”
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