Mole-Rat Siblings

Pictured in the family portrait above are representatives from the three recent naked mole-rat litters born to Pacific Science Center.



The largest mole rat at the bottom of the picture is from Elphaba’s litter born on August 26, 2009, the first successful pups this colony has had in over two years. The mother gave birth to seven pups of which two still survive. These two remaining pups have thrived and grown to about 33 grams in the past eight months. As most of our adult naked mole-rats weigh between 50-60 grams, this means these guys are over halfway full-grown! Not too shabby!

The second-largest naked mole-rat (top left) is from the September 20, 2009 litter, which was the first successful litter for Galinda. From her litter of seventeen pups, six pups have survived and they are just trailing the members of the August litter in weight and size. They are now ranging between 24 and 32 grams. Our biggest problem is trying to tell them apart!


The smallest guy is from Galinda’s March 16, 2010 litter of nineteen. There are thirteen pups from that litter that are still alive and thriving today! We have not yet weighed them because they’re so small and we don’t want to injure them. However, they appear to have just about doubled in size since birth. They seem to be growing at a pretty healthy pace, comparable to the members of the older litters.

How big can our naked mole-rat colony get? Stay tuned because it looks like Galinda is pregnant again!


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Cecotropes

What is that naked mole rat doing? Pacific Science Center's mole rat colony provokes this question frequently, but never more so than when animals solicit cecotropes.



The cecum (pronounced see-kum) is a portion of the digestive system in some species of animals, located between the small and large intestine. When food passes into the large intestine, the indigestible fiber is passed through as normal feces. However, portions that still contain nutrients are pushed back into the cecum where they are broken down into starches, sugars and vitamins. This material is then passed as cecal pellets or cecotropes, which the animal reingests.

Yes, the animal eats them. To a human, this is a strange concept. But to a naked mole rat with a diet high in fiber and low in calories, every bit of nutrition must be captured. By recycling nutrients that cannot be absorbed the first time, the animal is able to survive on a diet that would not support many other species. You can often watch a mole-rat assume a curled up sitting position allowing their head to reach far enough to ingest their own pellets.

Cecotropes are more than just nutrient-rich pellets. They also contain beneficial live cultures which the mole-rats need to properly digest their food. Baby naked mole-rats do not yet have these microbes and need to get them in order to survive. So as they begin to eat solid food, they will solicit older animals and beg for cecotropes. Late in her pregnancy, when her mobility is limited, the queen will also demand pellets.

Mole-rats do not normally produce these pellets on demand, and donor animals may be seen jumping or shaking violently in the process of producing them. Often when pups are involved, it looks as though an older animal may harm a pup, when in fact it is helping.

The ability and need to produce cecotropes may be part of the reason naked mole-rats are eusocial. All mammals need nutrition from their mother in the form of milk. For mole-rat pups, cecal pellets are a second form of necessary nutritive care, and one that can be provided by any member of the colony. This ability gives the queen a shorter turn-around time to focus her nutrient store on producing the next litter, while workers continue to provide for the existing pups.

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Fresh Sheet - April 23, 2010

“Fresh Sheet” is our weekly shipment report of pupae on display in the emerging window. Visit Pacific Science Center’s Tropical Butterfly House and meet our newest residents.



Costa Rica

10 - Agraulis vanilla (Gulf Fritllary)
37 - Anartia fatima (Banded Peacock)
11 - Battus belus (Belus Swallowtail)
20 - Battus polydamas (Polydamus Swallowtail)
11 - Caligo atreus (Yellow-Edged Giant-Owl)
11 - Caligo eurilochus (Forest Giant Owl)
11 - Caligo memnon (Owl Butterfly)
16 - Catonephele mexicana(Mexican Catone)
22 - Catonephele numilia (Numilia)
11 - Chlosyne janais (Crimson Patch)
20 - Colobura dirce (Mosaic butterfly)
29 - Danaus plexippus (The Monarch)
25 - Dryadula phaetusa (Banded Orange Heliconian)
12 - Dryas iulia (Julia Longwing)
26 - Heliconius charitonius (Zebra Longwing)
26 - Heliconius doris (Doris Longwing)
11 - Heliconius eleuchia (Eleuchia Longwing)
10 - Heliconius erato (Small Postman)
40 - Heliconius hecale (Tiger Longwing)
03 - Heliconius hewitsoni
34 - Heliconius ismenius (Ismenius Longwing)
10 - Heliconius melpomene (Postman)
11 - Heliconius sapho (Sapho Longwing)
09 - Heliconius sara (Sara Longwing)
13 - Heraclides anchisiades (Ruby-spotted Swallowtail)
17 - Hypna clytemnestra (Silver-studded Leafwing)
09 - Mechanitis polymnia (Polymnia Tigerwing)
38 - Morpho peleides (Blue Morpho)
34 - Myselia cyaniris (Blue Wave Butterfly)
11 - Papilio cresphontes (Giant Swallowtail)
16 - Papilio polyxenes (Black Swallowtail)
05 - Parides iphidamas (Iphidamas or Transandean Cattleheart)
11 - Phoebis argente (Apricot Sulfur)
35 - Phoebis philea (Orange Barred Sulfur)
17 - Siproeta epaphus (Rusty-tipped Page)
16 - Siproeta stelenes (Malachite)

Total = 648

We received a big shipment of pupae this week from Costa Rica including three species we rarely see: Heliconius eleuchia, Heliconius hewitsoni, and Phoebis argente. Come visit the Tropical Butterfly House and see them for yourself!


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Lydia Shedding

A few weeks ago, our Animal Caretakers and a few lucky visitors were able to witness something really special (and really cute!). Lydia, our adorable leopard gecko, was shedding! Luckily for you, one of our caretakers, Brianna Todd, had a video camera on hand, and was able to capture some of this remarkable activity.




Did you know that every animal sheds their skin? Even humans??? Humans, like most mammals, shed their skin pretty much constantly. Tiny particles of skin are sloughed from our skin all day long, although you may only notice it when you have dry, itchy skin or a sunburn. But check out that dust you’re collecting on the top of your book shelf or even on your coffee table, and you’ll find plenty of evidence for human shedding. A good portion of the dust that exists in our homes is made up of dead skin cells! Kind of gross right?

Lizards and snakes also shed their skin, although they actually make less of a mess than we humans. Because their skin is made up of scales, these reptiles must shed their skin all at once. In snakes, the shed skin will often come off in one piece. Because lizards have legs, it’s a little bit harder for them to shed in one piece, so it usually comes off in large pieces.

Many lizard species, including leopard geckos, eat their old skin as they pull it off. This may sound kind of gross but it’s actually another great adaptation. Not only does it leave no mess behind, it’s an efficient way for the animal to consume those extra vitamins and calories that are in their old skin.

But that’s enough talk for now. The video really says it all. So check it out, and the next time you visit Lydia at Pacific Science Center, congratulate her on a job well done.

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