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About Author: April Gorow

Posts by April Gorow

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Bones on the Beach

The team repositions the whale skull for better access for cleaning, measuring, and sample collection.

The team repositions the whale skull for better access for cleaning, measuring, and sample collection.

The Wildlife Disease Laboratories of the San Diego Zoo Institute for Conservation Research and the San Diego Natural History Museum (SDNHM) have had a long-time working relationship. So when Scott Tremor, the mammologist at SDNHM and a long-time friend of mine, called me in March to tell me about his latest adventure and make an interesting proposition, we were intrigued. A 30-foot-long juvenile humpback whale had died, and the carcass had washed ashore at Pelican Point, on the tip of Point Loma. Humpback whales are relatively rare off San Diego’s coastline, so the museum wanted to preserve the specimen for its collection. It had laid on the beach in the sun for over a month, and Scott was collecting volunteers to help clean the bones.

Having never necropsied a whale and being unfamiliar with the anatomy, I thought it would an amazing experience. This rare opportunity also enticed a few coworkers and two pathologists (Dr. Jenny Bernard, Dr. Andrew Cartocetti, Megan Varney, and Rachael Keeler) to put on their Tyvek® suits and boots and help out. With the warning that the carcass may have washed away overnight and may not be there when we arrived, we met up with other volunteers at the San Diego Natural History Museum and headed to the beach.

Pelican Point is a relatively narrow beach surrounded by a high cliff. This beautiful spot, part of Cabrillo National Monument, is closed to the public—the only way to reach it is down a cliff wall using a knotted rope. We timed our excursion to coincide with low tide, so we could access the beach and the whale. There, we were met by Southwest Fisheries Science Center employees, who are responsible for testing tissues and collecting measurements on all beached cetaceans. Dr. Thomas Deméré, curator of paleontology at the SDNHM, led us through the process. One of his areas of expertise and interest is in the evolutionary history of baleen whales, also known as the mysticetes. He explained that baleen species (humpback, fin, blue, minke, right, and grey whales) are filter feeders, but have all evolved different feeding strategies. Fossil evidence shows that all baleen species evolved from toothed whales. In studying today’s mysticetes , scientists have discovered that baleen whale embryos develop upper and lower teeth that simply never erupt. At some point the teeth are reabsorbed and baleen is formed. Because baleen is made of keratin, it rarely fossilizes and has not been studied much—making it important on this excursion to comb the beach in search of the sloughed baleen in addition to recovering the whale’s bones.

When we arrived, the whale looked like a white-grey mound. The goal of the day was to disarticulate the skull from the body and move it to the base of the cliff. Naturally, the tide washing over the carcass had removed some of the flesh exposing some bone, but there was still a lot of work to be done. The soft, rubbery flesh was hard to cut through and the sand dulled our knives immediately. Tom was amazing at directing us the best way to maneuver the skull so we could cut away the muscles. In the end, the strength and endurance of so many people accomplished our goal; we separated and lifted the 300-pound skull to a safe place on nearby rocks. All the while, a pleasant breeze of fresh ocean air kept the smell away. It wasn’t until later in the car ride home we realized we smelled like the hold of a fishing boat!

As you would expect, Scott and his volunteers made many more trips to the beach to recover as many bones as possible, stacking them at the base of the cliff. On April 14, the skull was placed in a sling, and the U.S. Coast Guard airlifted it first to a nearby parking lot, then on to a spot where it was buried so local insects could finish cleaning the bones. All of the other bones were carefully moved assembly-line style by a group of volunteers. It was front-page news in the local media that day! What a great opportunity we had collaborating with our neighbors at the San Diego Natural History Museum to turn a tragedy into valuable learning experience.

 

April Gorrow is a senior pathology technician at the San Diego Zoo Institute for Conservation Research. Read her previous blog, Nature’s Excellent Engineering Feat: The Egg.

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Nature’s Excellent Engineering Feat: The Egg

This kagu egg is just one example of nature's egg-cellent engineering feats.

This kagu egg is just one example of nature’s egg-cellent engineering feats.

Have you ever wondered why eggs are shaped the way they are? Or why egg shape varies with the species? Most eggs have one tapered and one wider end to ensure they roll only in a circular pattern. This ensures that the eggs do not roll out of the nest when they are turned by the parents. Some species lay eggs with a more pronounced small end, which make them roll in a tight circle. For example, seabirds like murres nest strictly on rocky cliffs and use no nest material at all. The elongated shape of their egg makes it less likely to roll off the cliff edge. Birds that make deep cup-shaped nests typically have rounder eggs, because there is less risk that the eggs will roll out of the nest when turned. Nature’s exquisite engineering continues inside the egg, too!

The egg itself is a self-contained home, supplying all the nutrients and safety for the growing chick inside. The duration of incubation varies, but all chicks will grow until there is so little space inside that it is difficult to move. When it is time to hatch, the chick has to get into the proper position, with the head under the right wing and the beak pointed upwards toward the larger end of the egg (being in the wrong position can be fatal). The large end of the egg has an air-filled space called the air cell. The chick must use its beak to pierce the air cell membrane so it can start breathing the air inside. As CO2 builds up in the air cell, it triggers the yolk sac to retract into the chick’s abdominal cavity, getting the bird ready for life outside the egg. The next step is to break out of the shell.

The beak has a hard, sharp, triangular shaped structure, called an egg tooth, on the top of the beak that assists in breaking through the eggshell. The chick uses its legs to rotate as it pecks through the shell until a hole is large enough to break out of completely. Once outside the shell, the chick can rely on its yolk sac for energy and nutrients until it is getting enough food from its parents, or is feeding on its own.

With such a complicated process there are bound to be occasional problems with completing the incubation and hatching process. But when these problems arise, we can learn from them and provide helpful feedback for our animal care staff, enabling them to make management adjustments that will maximize the reproductive success of the many amazing species of birds we have in our care.

April Gorrow is a Senior Pathology Technician at the San Diego Zoo Institute for Conservation Research.

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Beware of Crunchy Figs!

Here's a Moreton Bay fig fruit sliced in half.

The fruit of a Ficus sansibarica provides a cozy home for fig wasps.

Recently, the Wildlife Disease Laboratories received an interesting request from Seth Menser, a senior horticulturist at the San Diego Zoo, asking if we could take pictures of plant parts under the microscope. “I would really like to do a couple of shots of a fig cut in half with the fig wasps still inside. I have the figs needed for the shots. And, if you have never seen inside a fig, with the fig wasps, it is a very incredible thing to look at!” We were curious, so agreed to help.

Fig wasp

This amazing view of a fig wasp was taken in our Wildlife Disease Laboratories.

Seth brought up several figs from a Ficus macrophylla, commonly known as a Moreton Bay fig. These trees originate in the subtropical rain forest of eastern Australia but do well in frost-free climates such as ours. These majestic trees can reach up to 200 feet (60 meters) with long, aerial roots providing the tree with additional support to hold up the immense canopy. Seth brought several figs ranging from green and firm to dark maroon with spots on the outside. He explained the life cycle of the fig and the fig wasp as he cut them in half, and we set up the cameras.

Here's one

This female fig wasp has her wings. Is she ready to fly to a new fig?

Ficus trees are unique because the flowering parts of the plants are inside the fruiting parts (figs), making it difficult for insects to pollinate the trees. Thus begins the cooperative relationship with the fig wasp. The fig provides refuge and a food source for the wasps, and, in turn, the wasps pollinate the tree.

To begin the cycle, a tiny female fig wasp enters into a narrow opening (ostiloe) at one end of the fig. While wiggling into this small hole, she often looses a wing or antenna. Safely inside, she lays her eggs. As she is wandering through the fig, she spreads pollen from the fig she hatched in, thus helping the fig tree produce viable seeds. The cycle of the female wasp is complete, and she dies. Her eggs hatch, and the young wasps grow, finding food and refuge in the fig. Interestingly, only female wasps grow wings and leave the fig. The males live their entire life in the fig. Their function is to mate with the females and chew small openings through the fig’s wall for the females to escape, and the cycle begins again.

How many fig wasps can you find in this fig?

How many fig wasps can you find in this fig?

We were totally fascinated by the story. Using a dissecting scope with a camera attachment and a macro lens on a photo stand, we were able to capture the intertwined life cycles of the fig and the wasp. We photographed the narrow ostiole of the immature smooth fig where the female enters. Mature figs looked completely different on the inside. They were soft and fleshy, with delicate flower structures and seeds lightly attached to the inner walls. Each mature fig contained several wingless male wasps, and Seth was lucky enough to find one female flighted wasp.

At first glance, theses tiny wasps are difficult to see. The magnification helps, but a keen eye is needed to see them. How many can you find?

April Gorow is a senior pathology technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, We Never Stop Learning.

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We Never Stop Learning

Did you know that hedgehogs evolved 50 million years ago in San Diego County?

Did you know that hedgehogs evolved 50 million years ago in San Diego County?

Dioramas, specimen jars, and stacks of books are all images that come to mind when you think of natural history museums. Museums are not just filled with primary school students on field trips but with invaluable collections. Museum curators are not just librarians cataloging their specimens but scientists and researchers helping to save species. With the number of endangered species increasing, museums have evolved into a major resource for biologists and other researchers who study genetics, taxonomy, comparative anatomy, and even behavior.

Field biologists need to understand the animals they study. They need to understand each animal’s living requirements (food, water, space, territory, and reproductive strategies), but also anatomy and physiology. It is important to understand what makes an animal jump, fly, and live without water for long periods of time. So off to the museum they go.

We have established how important museums are, but where does the museum get their specimens? One place is from us. San Diego Zoo Global has an immense and diverse collection exceeding 7,500 animals. Many of these animals are not displayed anywhere else in the US, which makes the collection unique not only to visitors but to museums and researchers. After an extensive necropsy and investigation of an animal’s death, the body may be saved for a museum.

One of the museums we work with is our neighbor, the San Diego Natural History Museum. Phillip Unitt, the museum’s curator of birds and mammals, boasts that “donations from the San Diego Zoo’s Wildlife Disease Labs have given our collection a worldwide dimension it would otherwise not have.”
Phil likes to share the story of hedgehogs during museum collection tours. Hedgehogs were evolving 50 million years ago in San Diego County. Though now extinct in North America, paleontologists at the museum are able to compare the local fossilized remains to the African hedgehog carcasses received from the San Diego Zoo.

Animals are amazing in their diversity, anatomy, physiology, and adaptability. We continue to learn about them even after death. Archiving and sharing tissue samples from them provide rare and extremely valuable resources for current disease investigations and future research.

April Gorow is a research coordinator for the Wildlife Disease Laboratories, San Diego Zoo Institute for Conservation Research. Read her previous post, Victor Lives On.