A Mermaid’s Purse: A Surprise Discovery Within

Recently, as I was volunteering at a local marine life center, a pair of fishermen brought in a large mermaid’s purse as they called it – offering it to the center for educational purposes. Of course, the staff and volunteers jumped at the chance to showcase this animal in our aquaria.

I’m delighted that this recent discovery aligns with the current Nature Book Club theme – learn more about this monthly link-up below.

image of a mermaid's purse or egg case from a big skate

A mermaid’s purse is an egg case or capsule of oviparous (egg laying) sharks, skates, and chimaeras. The egg cases are purse-shaped with long tendrils at the corners that serve to anchor them to structures on the sea floor.

The size of egg cases vary, depending on species. Most contain a single embryo but egg cases of larger species, like the big skate, can contain seven. As it happens, the mermaid’s purse that was brought to us was that of the big skate, Raja binoculata.

Though I had previously observed skates and rays at larger aquaria (most notable Monterey Bay Aquarium and the Aquarium of the Pacific – both in California), I had yet to observe them in the wild. The director was eager to provide the students, volunteers, and many visitors the opportunity to observe the development of the embryos up close.

Skates & Rays

This recent experience has inspired me to learn more about the skates and rays. I immediately went to our local library and checked out a couple books to get me started – even as an adult, I often go to the children’s section to find non-fiction books on topics of interest. I love the way authors bring it down to their level and the two highlighted here do just that.

Raja binoculata photo by Scott Stevenson – visit his site for more amazing photographs

There are over 500 species of skates and rays in the world and are easily distinguished from other fish by their disc-shaped, dorso-ventrally (i.e. from top to bottom) flattened bodies and expanded pectoral fins which attach to the sides of the head.

Their basic body shape allows them to live on or very close to the bottom of the ocean, where they bury themselves in mud or sand to ambush prey and avoid predators. Along with their basic body shape, they are characterized by ventral gill openings, eyes and spiracles located on the top of the head, pavement-like teeth, and lack of an anal fin.

Skates and Rays is a great book for children to introduce them to the subject. Any beachcomber who finds a “mermaid’s purse,” an egg case from a skate, must wonder what sort of creature can emerge from such a curiously shaped item. This book, part of the “Living Ocean” series, explores the world of rays and skates, of which there are more than 150 species.

Closely related to sharks, these animals make up a subclass of cartilaginous fish. Instead of having skeletons made of bone, elasmobranchs have skeletons made of soft, pliable cartilage. Like rays, skates are usually flat, with a long tail.

This book examines the behavior, habitats, and anatomy of these intriguing swimmers, describing how they catch prey, why they are important to oceans, and why many are in danger.

Another good choice is The Nature Company Guide to Sharks & Rays. This book has real photographs of sharks on every page, and rays are featured more prevalently than in most other books on the same topic. The species is clearly identified and portrayed in the field guide chapters, and following that are details about choice diving locales around the world.

It will be especially useful to the teen reader or marine naturalist/hobbyist. The information is well organized, detailed, and scientifically accurate. For someone less familiar with scientific terms, it could be a bit heavier, as it tends to use many terms, such as pelagic and elasmobranch, with only a brief definition provided.

A Mermaid’s Purse

Egg cases are made of collagen protein strands and most would describe the exterior texture as rough and leathery. Some egg cases have a fibrous material covering the outside of the egg case, thought to aid in attachment to substrate.

Egg cases without a fibrous outer layer can be striated, bumpy, or smooth and glossy. Egg cases are typically rectangular in shape with projections, called horns, at each corner. Depending on the species, egg cases may have one or more tendrils.

The mermaid’s purse that was brought into the learning center was prepared by one of the graduate student volunteers from the university. He carefully cut a hole into the flat side of the egg case and adhered a clear plastic covering. This provided a window by which we can watch the development of the embryos within as you can see from the video above.

Raja binoculata

The big skate is the largest species of skate (family Rajidae) in the waters off North America. They are found all along the Pacific coast from Alaska to Baja California, typically from the intertidal zone to a depth of 120 m (390 ft).

These impressive animals feed on benthic invertebrates and small fishes. As I stated previously, they are unusual among skates in that their egg cases may contain up to seven eggs each. This species is one of the most commercially important skates off California and is sold for food, though compared to other commercial fisheries, it is of only minor importance.

Typically caught as a by-catch of trawlers, fisheries have begun to market it more as a result of higher market value. Unfortunately, the big skates’ slow reproductive rate gives cause for some concern but population data is limited.

simple graphic image of tree with text The Nature Book Club

Welcome to the The Nature Book Club Monthly Link Up. Devoted to connecting children to nature, the monthly link up will begin on the 20th day of each month.

We welcome your nature book and activity related links. Read on for more details and for a giveaway!

See all the great posts from The Nature Book Club’s co-hosts in April:

The Nature Book Club is brought to you by these nature loving bloggers which are your co-hosts. Are you following them? If you don’t want to miss anything, be sure to follow each one.

Bird Nest/Eggs nature study pages from Barb at Handbook of Nature Study

Eggs: Nature’s Perfect Package from Erin Dean at the Usual Mayhem

Getting Started with Citizen Science – Nest Watch from Eva Varga

From Egg to Sea Turtle Unit Study & Lapbook from Tina’s Dynamic Homeschool Plus

Eggs Nature Study Free Printable Word Search from Faith and Good Works

Egg Scavenger Hunt with Egg Carton from Katrina at Rule This Roost

Felt Bag Handicraft from Melanie at Wind in a Letterbox

Clay Eggs Project from Emily at Table Life Blog

Online Book Club from Dachelle at Hide the Chocolate

Egg Identification Nature Bingo {Free Printable} from Cassidy at Freshly Planted

image of a stack of books in the grass with text overlay listing monthly themeParty Rules

  • Choose an engaging nature book, do a craft or activity, and add your post to our monthly link up.
  • The link up party goes live at 9:00 a.m. EST on the 20th of each month and stays open until 11:59 p.m. EST on the last day of the month. Hurry to add your links!
  • You can link up to 3 posts. Please do not link up advertising posts, advertise other link up parties, your store, or non-related blog posts. They will be removed.
  • By linking up with us, you agree for us to share your images and give you credit of course if we feature your posts.That’s it!
  • Let’s party.


Exploring Ecology: The Many Parts of a Streambank

The forested land along rivers and streams is known as the “riparian zone”. Riparian comes from the Latin word ripa, which means bank. Riparian zones are areas of transition where the water and land meet and they offer many benefits to wildlife and people.

Only in the past few decades have scientists and land use specialists come to realize the value of riparian zones. Amongst the most diverse biological systems on earth, riparian zones offer many critical ecological benefits:

Overhanging vegetation and trees shade the stream channel, keeping the water nice and cool.

The vegetation along the streambank helps to hold on to the soil and prevent erosion.

These stream side wetlands also act like huge sponges absorbing and filtering the water, which reduces high flows into the stream.

riparian area studyParts of a Streambank

Stream Channel

This zone is the wetted area located below the average water mark or water level. Generally, the streambank soils next to the stream channel have the most erosion because of the constant water flow. When plants are present in this area, the plants are rooted into the soil beneath the water. Vegetation includes herbaceous species like sedges, rushes, and cattails and are found in the low energy streams or in protected, slow-moving areas of the stream.

Sedges have edges, rushes are round, and grasses have bumps all the way to the ground.

Riparian Zone

The riparian zone is the area between the average water mark and the average high water mark. The plants that are found here thrive along the banks so long as their root systems are able to access surface water and subsurface flow. When a riparian area contains healthy, native plants, there is less erosion. This zone contains predominately shrubs, willows, and other water-loving plants.

Floodplain

The floodplain is a relatively flat area located adjacent to a river or stream. This area can experience occasional or periodic flooding. When a river breaks its banks and floods, it leaves behind layers of sediment – rock, sand, mud, and silt. These materials gradually build up to create the floor of the floodplain. Here, the soils are a mix of sand, gravel, loam, silt, and clay. These areas are important aquifers, filtering the water drawn from them through these soil combinations. Plants found here often contain a mix of riparian and upland plants and trees – willows, dogwoods, alder, and birch trees as well as large shrubs.

A few years ago, my STEM Club spent the day inundating ourselves in Stream Ecology. Read this post to discover other activities you can use to engage your students.

Transitional Zone

The transitional zone is located between the floodplain and the upland zone. Here, the area is rarely affected by stream flow and floods only once every 50 or so years. This zone is comprised of drier upland trees and large shrubs that do not need to access the stream water or subsurface flow with their roots.

Upland Zone

The uplands consist of land where drier vegetation can be found. The plants and trees here no longer depend upon the surface or subsurface flow of stream water for their survival. However, the taller trees in this zone do create a valuable forest canopy that helps to shade the stream.

Previously, we partnered with the USDA Forest Service to hear first hand how a forester manages a forest and to get a chance to use the real tools of the trade. Read more of our experience in my post, Field, Forest, & Stream: Forest Ecology.

riparian area survey tableRiparian Area Survey

Materials

  • Pen/pencil
  • Tape measure
  • Field notebook
  • Colored pencils (optional)

Procedure

  1. Copy the table above into your field notebook.
  2. Go to a nearby stream and select an area of the streambank and riparian area to study. Measure the area that you have selected.
  3. Complete the table checking the box for each vegetation type you see. If you are able, identify as many as possible.
  4. Choose a section of the length of the stream surveyed and draw the stream and riparian area from a bird’s eye view (from above).
  5. Once you have the basic outline of the area (stream channel, banks, riparian area), begin by marking where you see each type of trees, shrubs, ferns, etc. Use the symbols in the table above to simplify your sketch.
  6. Make sure to draw an arrow in the stream to show the direction of water flow.

Conclusion

  1. Based on your observations at this site, describe any human influences on the riparian area.
  2. What features of the riparian zone do you think are important to fish?
  3. Do you notice any patterns of certain vegetation types and where they are located in relation to the stream? Why do you think that is?

Ecology ExplorationsScience Logic

You will find more activities like this one in my Ecology Explorations curriculum available for purchase in my store. The Life Logic: Ecology Explorations unit that I have developed for middle school students is an easy to implement, hands-on way to learn about ecology. Students will love getting outside, collecting data, and experiencing the physical factors that influence the animal and plant communities in their local area first hand.

 

Nettie Stevens: The Genetics Pioneer Who Discovered Sex Chromosomes

At a time when women mostly married and stayed home, or were teachers or nurses if they wanted to work, Nettie Stevens became a research scientist and her discoveries changed genetics forever.

NettieStevensGeneticsPioneerOnce she graduated with her PhD in 1903, she and a colleague (Thomas Morgan) began a collaboration on the controversial and unresolved question of how sex is determined in the developing egg. Did external factors, like food and temperature, set the sex of an egg? Or was it something inherent to the egg itself? Or was sex inherited as a Mendelian trait?

She examined the yellow mealworm, Tenebrio melitor, and made a striking observation. She had observed that this species produced two classes of sperm: a type that carried ten large chromosomes, and a type that carried nine large and one small chromosome. Body cells in the females contained 20 large chromosomes while males carried 19 large and one small chromosome.

Stevens reasoned that when an egg is fertilized by a sperm that carries the small chromosome, the result is a male offspring. The presence of the small chromosome might be what decided the individual’s “maleness.”

She published her research in 1905 and it eventually evolved into the XY sex-determination system we know today: The father’s sperm, which can carry either X or Y chromosomes, determines the sex of the offspring. Before Stevens’ work, scientists thought that the mother or the environment determined if a child was born male or female.

Biography

Nettie StevensNettie Maria Stevens was one of the first American women to be recognized for her contribution to science. Yet she didn’t begin her career in genetics until later in life.

Stevens was born on July 7, 1861, in Cavendish, Vermont, to Ephraim and Julia Stevens. After the death of her mother, her father remarried and the family moved to Westford, Massachusetts.

Initially, Stevens taught high school and was a librarian for more than a decade. Her teaching duties included courses in physiology and zoology, as well as mathematics, Latin, and English. Her first career allowed her to save up for college; at the age of 35, she resigned from a high school teaching job in Massachusetts and traveled across the country to enroll at Stanford University in California.

At Stanford, she received her B.A. in 1899 and her M.A. in 1900. She also completed one year of graduate work in physiology under Professor Jenkins and histology and cytology under Professor McFarland.

Stevens continued her studies in cytology at Bryn Mawr College, where she obtained her Ph.D. Here, she was influenced by the work of Edmund Beecher Wilson and by that of his successor, Thomas Hunt Morgan. Her work documented processes that were not researched by Wilson and she used subjects that he later would adopt along with the results of her work.

At age 50 years, only 9 years after completing her Ph.D., Nettie Stevens died of breast cancer on May 4, 1912 in Baltimore, Maryland.

Bring it Home

▶︎ Dive into Genetics with a fun unit study

▶︎ Enjoy a slide show presentation on genetics

▶︎ Try out this jigsaw format activity to explore the sex determination mechanisms of seven organisms, Xs and Os

▶︎ Learn about the Father of Genetics: Gregor Mendel

▶︎ Try this Gummy Bear Genetics lab from The Science Teacher (a NSTA publication)

▶︎ Use pipecleaners and beads to show how genes and chromosomes are inherited in this Pipecleaner Babies lab.

▶︎ Use pennies to do this How Well Does a Punnet Square Predict the Actual Ratios? lab.

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

The bloggers of the iHomeschool Network have teamed up to create fun and original unit studies on fascinating people who were born in July.

 

Science with Harry Potter: Care of Magical Creatures (Zoology)

Care of Magical Creatures is an elective at Hogwarts, available to upper classmen. Throughout the course, students learn about a wide range of magical creatures and are taught about the care and husbandry.

Similar to herbology, the further into a student’s education the more difficult and dangerous the creatures become. The witches and wizards who succeed in the subject later become Magizoologists, like Newt Scamander.

Magical CreaturesFor this class students are required to become familiar with the many magical creatures you may encounter both at Hogwarts and in the outside world. Students should begin with the following:

  • Owl
  • Hippogriff
  • Phoenix
  • Unicorn
  • Werewolf
  • Centaur
  • Basilisk
  • Elf

C’mon, now, get a move on! Got a real treat for yeh today! Great lesson comon’ up! Everyone here? Right, follow me!” ~ Rubeus Hagrid at his first Care of Magical Creatures lesson

Students are required to keep a field notebook in which a two-page spread is created for each magical creature studied. For each magical creature you study:

  1. Make a sketch of the creature, labeling important features
  2. List any historical or literary references to the creature
  3. Describe its natural habitat
  4. Discuss its habits, temperament, and relationship to humans
  5. List its magical properties
  6. Explain the care and feeding of the creature

Advanced students may choose additional magical creatures to study. Take care to choose wisely, as your knowledge of magical creatures could one day prevent a terrible injury or death.

Magical Properties of Dragons

You’ve likely already discovered the magical property of dragon scales while researching and preparing your field notes above. Now you will learn about the properties of dragon skin and dragon down (the fluffy feathers from underneath the wing).

Young wizards and witches should have adult supervision as all parts of a dragon are highly flammable. A fire-proof cauldron is advised.

Dragon Skin: take thin slices of dragon skin and hold them next to an open flame. Bend the skin, squeezing until it bursts. You should see tiny sparks fly as the fire-breathing properties are released. This should be done very close to the flame.

Dragon Down: Put a small quantity of dragon down into a cauldron. Touch the end of a 9 volt battery lightly to the down to release the fire-breathing properties.

(Note to professors: muggles will know these items as orange peel and steel wool.)

Genetics

Students watch a video clip from Harry Potter and the Goblet of Fire to learn about genetic traits. Specifically, they realize that the ability to speak parseltongue (being able to speak to snakes) is a genetic trait possessed by some characters and their parents. Students explore the use of Punnett squares to predict trait inheritance, learning about genotypes and phenotypes.

This post is part of a five-day hopscotch. Join me each day this week as we dive into each course.

Herbology (Botany)

Care of Magical Creatures (Zoology) – this post

Potions (Chemistry)

Alchemy Astronomy & Divination (Geology)

Magical Motion (Physics)

Science with Harry Potter: Herbology – The study of plants and fungi (Botany)

Herbology is the study of magical and mundane plants and fungi. It is a core class and subject taught at Hogwarts School of Witchcraft and Wizardry for the first five years of a student’s education.

herbology

Herbology

Throughout each term, students learn to care for plants as well as learn about their magical properties and how they may be used medicinally. The further into a student’s education the more difficult and dangerous the plants become.

“Three times a week they went out to the greenhouses behind the castle to study Herbology, with a dumpy little witch called Professor Sprout, where they learned how to take care of strange plants and fungi, and found out what they were used for.” ~ Harry Potter and the Sorcerer’s Stone

All first year students are required to familiarize themselves with the herbs listed below.

  • Chamomile
  • Tarragon
  • Yarrow
  • Caraway
  • Horseradish
  • Dill
  • Aloe Vera
  • Silver Birch
  • Garlic
  • Tumeric

herbologyAs students work through their self-guided journey, they are required to keep a field notebook in which a two-page spread is created for each plant or fungi studied. Each spread is required to include the following information:

  1. Give common name as well as Latin names (genus and species) and family
  2. Press a specimen of the plant (if possible)
  3. Make a sketch of the plant, colored appropriately
  4. Label key parts of the plant, pointing out important features
  5. Explain its cultivation and care
  6. Give a brief natural history of the plant (describe growth cycle, natural range, etc.)
  7. List its household and medicinal uses both presently and historically
  8. Describe its magical properties (if any)

Take it Further

Enjoy a cup of Chamomile tea before bedtime or a glass of birch beer with your noonday meal.

Explore the many wildcrafting and herbal remedies described at Learning Herbs.

Enjoy the fun board game, Wildcraft: An Herbal Adventure.

Research the native plants in your local area and learn how native peoples used them for food and medicine.

Visit a native elder, if possible, and learn to how to harvest and prepare these plants for personal use.

As you advance in your studies, be sure to add each new plant to your journal.

This post is part of a five-day hopscotch. Join me each day this week as we dive into each course.

Herbology (Botany) – this post

Care of Magical Creatures (Zoology)

Potions (Chemistry)

Alchemy Astronomy & Divination (Geology)

Magical Motion (Physics)

Problem Based Learning with William & Mary

This past school year, my kids and I have been inundated in the study of coastal ecology. The kids worked through the curriculum along side me. Memorizing vocabulary and understand the ecology concepts came easily to them as I’ve immersed them in nature studies since they were toddlers.

We enjoyed several memorable field trips whereupon we developed a list of questions based on our observations: Roosevelt Elk at Dean’s Creek & Foraging for Mushrooms.

We also engaged in several nature study investigations to learn more about the organisms we had observed: Slugs, Snails, and Sea Hares Our Native Maple Trees.

I received this product for free and am being compensated for the time to write the review.  This is an honest review of the product.problem based learning

Yet all along, I knew in my heart that something was missing. While they were engaged in our lessons and activities, they were not captivated. I wanted them to be challenged. I wanted them to struggle to find answers to their questions. I wanted a problem based learning experience.

The units created by William & Mary from Kendall Hunt Publishing provide the perfect challenge. The books provide a wonderful framework for getting students to think, presented in such a way that they want to solve the problem. Along the way, students experience the processes and tools a scientist may use when presented with a difficult problem.

What is Problem Based Learning?

Problem Based Learning is a student-centered pedagogy in which students learn about a subject through the experience of solving an open-ended problem. Students gain content knowledge and develop skills by working for an extended period of time to investigate and respond to an engaging and complex question, problem, or challenge.

When I was given the opportunity to review the William & Mary problem based learning materials, I immediately jumped at the chance. The Animal Populations unit (designed for grades 6-8) was the perfect fit to further our understanding of ecology and wildlife sciences.

william & mary

Problem Based Science Units by William & Mary 

The William & Mary science units introduce real-world problems to initiate scientific investigations. All units incorporate a problem based learning scenario as the catalyst for initiating the discussion of content and scientific investigation.

Students not only focus on specific content learning in science, but they also develop scientific investigation skills as a way to develop the thinking skills of a scientist. Students pose questions, then conduct experiments to answer those questions. They also identify independent and dependent variables, constants, and controls as a guide for quality investigations.

Animal Populations Unit

Animal Populations is centered around the problem of a growing population of deer in a fictitious rural community and the increasing number of people afflicted with lyme disease. The story begins with an email a mother writes to her spouse relaying the symptoms their son has developed.

Immediately, both kids were intrigued and were searching for possible causes. As the story unfolded with newspaper articles and additional personal accounts, they began to collaborate to find solutions to the problem.

In addition to staging the problem, the lessons lead students through the process of inquiry and experimental design. Each step is clearly outlined and in context with the big picture or ecology. We started each lesson with a discussion on the vocabulary and review of where we left off in our previous lesson.

I was really impressed with the lessons on the concept of models. While we are all familiar with physical models, the lessons clarified the meaning of conceptual and mathematical models in-depth. The lessons built on each other and really helped the kids (myself included!) understand the mathematical models of a deer population: exponential growth model and logistic growth model.

deer populationsOur favorite lessons were the field studies whereby we implemented a transect survey. We were fortunate at the time we implemented this unit to be able to partner with a local agency to take part in an ongoing bio-monitoring project at the national estuarine research reserve. Not only was our data useful in the context of our lesson but it was also critical for the success of their long-term estuarine research.

We all enjoyed this unit study as it was both challenging and fun. I look forward to implementing more problem based units in the near future.

Other Science Units

Kendall Hunt Publishing offers several other William & Mary science units to choose from, several have received National Association for Gifted Children’s Curriculum Studies awards.

* Where’s the Beach?—Grades 2-4 
* What A Find!—Grades 2-4  (See Erin’s review at Royal Baloo)
* Acid, Acid Everywhere—Grades 4-6
* Electricity City—Grades 4-6
* Nuclear Energy: Friend or Foe?—Grades 6-8
* Something Fishy—Grades 6-8
* No Quick Fix—Grades 6-8

Unit content has been aligned to national standards and meets national grade level standards as well as standards for grades that are two to three levels above the current grade.

Connect with Kendall Hunt

Follow Kendall Hunt Publishing on your favorite social media. By connecting with them you will get regular updates, information about their products, encouragement for teaching gifted learners as well tips and ideas.