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Monday, November 20, 2017

Species Fact Profile: Sand Tiger Shark (Carcharias taurus)

Sand Tiger Shark (Gray Nurse Shark)
Carcharias taurus (Rafinesque, 1810)

Range: Temperate and Tropical Oceans Worldwide
Habitat: Shallow Waters, Bays, Reefs
Diet: Fish, Crustaceans, Cephalopods
Social Grouping: Solitary, Small Groups
Reproduction: Breed in October and November.  Gestation period 6-9 months.  Females give live birth (eggs hatch within the mother's body) in sheltered areas, typically breeding once every two years. Believed to be mature at 4-10 years (females take longer to mature than males)
Lifespan: 35 Years (Wild Estimate)
Conservation Status: IUCN Vulnerable

  • Maximum length up to 6 meters and weighing up to 300 kilograms, but 3.5 meters long and weighing 95-110 kilograms is more typical.  Females are usually larger than males
  • Grey coloration, fading to dirty white on the underside, with some metallic brown or red spots on the sides
  • Snout is pointed and slender, and long teeth are visible even when the mouth is closed.  This gives the shark a fierce appearance, which results in their having a reputation for being more dangerous than they actually are
  • Although only two pups are usually born, a female may have hundreds of eggs inside their uterus,  The first pups to begin growth will eat the other, less-developed embryos in what is known as intra-uterine cannibalism
  • Populations at northern and southern extremes of the species range will migrate towards the equator in the winter and back towards the poles in the summer
  • Sometimes hunt cooperatively, working together to herd fish into congregations where they can be more easily seized
  • The first shark species to be granted legal protection.  Believed to be in decline, primarily due to overfishing for meat and fins, as well as accidental entanglements in nets set for other species; during 18th and 19th centuries, their liver oil was used in lighting

Zookeeper's Journal: Compared to the great white shark and many of the other large, predatory shark species, the sand tiger shark is a relatively placid fish, which adjusts well to life under human care.  As a result (and bouyed by the popularity inspired by its fearsome appearance), they are one of the most commonly kept large sharks in aquariums - they certainly were the first shark species that I ever saw growing up, and remain my archetypical "shark."  For large sharks, however, "easy" is a relative term with respect to captive care.  Large sharks don't swim in the wild as much as they glide; in an aquarium tank that is too small, they may have to swim much more actively than they would in the wild.  This sometimes results in a somewhat hunched posture for a shark.  The best tanks are the biggest ones which facilitate the constant motion that these sharks would employ in the wild.

Saturday, November 18, 2017

From the News: Chester Zoo successfully breeds rare Catalan newts

Earlier today, the news broke that the removal of a ban on the import of African elephant trophies into the United States has been reversed; the ban is now back in effect.  One good news item deserves another.  Here's a story that is not going to be getting social media all fired up or drawing lots of celebrity star-power, but is just as deserving of attention: the first captive breeding ever of the rare Montseny newt!  Congratulations to the Chester Zoo!


Catalan newt
 Experts have created a purpose-built breeding facility for the newts to ensure their bio-security. Photograph: Chester Zoo

Thursday, November 16, 2017

Elephant Trophy Ban Lifted


Not a zoo issue in particular, but one which many keepers are discussing today.  Today, the Trump Administration announced that it will be lifting a ban allowing the import of elephant hunting trophies from some countries in southern Africa. 

The announcement has been met with widespread condemnation from the keeper community.  There is a fear that this measure could promote the feeling that elephants are worth more dead than alive, that it could serve as a backdoor to smuggling ivory, or that monies supposed to be going to be conservation could be funneled elsewhere. 

The fact that one of the countries involved in this arrangement has undergone a coup this week isn't helping matter.  Nor is the fact that the President's sons are known to engage in the odd trophy hunt.  Maybe someone was hoping for some new decor for the Oval Office...

PHOTO: A Kenya Wildlife Services (KWS) ranger leads volunteers to carry elephant tusks to a burning site on April 20, 2016, at Nairobis national park for a historic burning of tonnes of ivory, rhino-horn and other confiscated wildlife trophies.

Wednesday, November 15, 2017

Just Because It's On the Internet...

Image may contain: plant and outdoor


This was making the rounds with a fury earlier this month.  A woman in Virginia was purporting to have evidence of a red panda (which, incidentally, looks not much like a red fox) in a suburban backyard.  Sure, it was a heck of a haul from Norfolk, where an red panda went missing from the  Virginia Zoo months ago, but crazier things have happened, right?

Right, but not in this case.  In this case, it was a prank that spread a little too far and a little too fast.  Someone took a photo of a red panda at a zoo and jokingly sent it to someone else as a "Hey, look what's in my yard!" joke.  That person immediately posted it on the Internet where, it is said, a lie can run around the world before the truth gets its shoes on.

Not that it was a deliberate lie, and I'm sure no one wanted it to build up and then dash the hopes of the Norfolk keepers.  It just goes to show that once something is online, it can definitely take a life of its own.

I have an annoying suspicion that this is going to keep popping up for sometime...

Sunday, November 12, 2017

Species Fact Profile: Axolotl (Ambystoma mexicanum)

Axolotl
Ambystoma mexicanum (Shaw, 1789)

Range: Central Mexico
Habitat: Lake Xochimilco
Diet: Algae, Aquatic Invertebrates
Social Grouping: Solitary
Reproduction:  Breed from March through June in the wild.  Sexually mature at 12-18 months.  Males dance to initiate courtship, deposit sperm packets for females to pick up.  Hundreds of eggs laid in mucous envelopes, glued to rocks and other substrate.  Hatch after 2-3 week incubation period.
Lifespan: 10-15 Years
Conservation Status: IUCN Critically Endangered, CITES Appendix II


  • Body length 30 centimeters.  Weight 125-180 grams.  Females larger than males
  • Demonstrate an extreme form of neoteny, in which salamanders do not fully undergo metamorphosis and retain their larval features, most notably their branch-like gills
  • If the habitat dries up, the normally larval-like axolotl is capable of undergoing metamorphosis and turning into a "normal" salamander.  Metamorphosis can be induced in captives by thyroid hormone injections
  • Coloration is dark brown or green, often blotchy.  Albinos are frequently bred and seen in captivity, but are not seen in the wild.
  • If wounded, they are capable of converting the affected cells into a stem-cell like state and regrow missing tissue, including whole limbs
  • Herons and other marsh birds are the primary natural predator; larger fishes have recently been introduced to the lakes where axolotls live, adding to the predation pressure.  They are aso consumed by local peoples
  • Common name means "water dog" in the Aztec language, referring to the Aztec god Xolotl, god of the dead and resurrected, as well as ugly beings 
  • Commonly used in biomedical research due to their unique properties.  Breeds very well in captivity; before breeding was established, capture of wild axolotls was a major form of population decline.
  • Major threat causing the decline of the species is habitat loss (one of the two lakes where tis species occurred no longer exists) and pollution from agriculture and sewage disposal, as well as the introduction of predatory fishes

Wednesday, November 1, 2017

A Leave of Absence

Due to some personal matters which have popped up, I'll be taking a brief leave of absence from the Blog - I expect to start up again in the second half of this month.  Hope to be back refreshed and ready in a few weeks!

Tuesday, October 31, 2017

Trick or Treat at the Zoo

Like every zoo and aquarium in North America, our zoo has Halloween events.  Like everywhere else, we call them "Zoo Boo" or "Boo at the Zoo", because zoo marketing staffs tend not to be too original, and they're suckers for an easy rhyme.  A small army of children (okay, a LARGE army of SMALL children) parades through the gates in search of candy.  There are a few events and games and some roaming animal ambassadors.

The next day is, inevitably, one of my least favorite days of the year, as it seems that the entire grounds of the zoo are covered with a fine coating of candy wrappers, trampled into the dirt by thousands of little sneaker-clad feet.

As I was scrapping the 867th trodden Tootsie Roll off of the pavement the other day, it occurred to me.  There is a depressing lack of animal-themed costume out there.  Looking back on my childhood, I don't think I went trick or treating as an animal once (well, not knowingly - I have seen pictures of my 3 year old self in a zebra costume, which I think is still hanging up somewhere in my parent's house).  I stopped trick or treating at a fairly early age, but many of my coworkers, at my zoo and around the country, still like to dress up as animals for Halloween.  Some get very detailed and very creative.

It would be neat to start trying to make this more of a thing by hosting animal-themed costume contests at our zoo.  We could judge them not only on their skill, but also their creativity.  Imagine someone showing up in a yellow sleeping bag, disguised as a banana slug?  Wearing a football helmet with horns attached as a bighorn sheep?  A bird of paradise costume, complete with the dance routine?  

To keep the theme interesting, the prize should be animal related.  A photo-op with the animal you were impersonating?  A behind-the-scenes tour?  An adoption certificate?  

There are tons of trick or treating venues out there to compete with for kids.  Perhaps it would makes ours stand out a bit more if we took the opportunity to emphasize what makes this one unique - animals.