Evolving to the Environment and Convergent Evolution

Hello everybody,

Now that you have gone through the animal kingdom, I want to give you some information about evolution. The first handout is on how the environment is a major influence on evolution. I compare the sister clades crustacea and insecta. Looking at their body systems, you will notice that the change from a lobster-like animal to an insect is all due to a complete change in environment.

Life on Land vs Life in Water

The second handout, a pdf from notes I gave to a class last year, is on convergent evolution. This is the subtext on the Life on Land vs Life in Water notes. If the environment is so important, animals from different groups should begin to look similar if they have similar niches (occupations) in an environment. And they can look at the three links below. The first link shows Ocean Ramsey, a shark conservationist, free-diving with a Great White Shark. First of all, she does not recommend people try this unless, like her, they have spent years studying shark behaviour. Secondly, notice how the shark swims.


Now watch the video at the link below. It is a GoPro video of dolphins swimming. Notice how similar the body of a dolphin is to that of a shark. Dolphins are grouped as toothed whales, so evolved from Pakicetus. Sharks evolved from ancestors that never walked on land. So, notice the differences in how they move compared to the shark.


Now watch this last video. It is a slow-motion video of dogs running on a beach. Notice how the back moves and how the tail goes up and down as the dog pulls its back legs under and the tail goes up when it stretches its spine again. Compare that to the way the dolphin swims, despite not having any back legs.


The dolphin and shark look similar because of the environment. However, the dolphin has an evolutionary history of living on land and is stuck with a body that initially evolved for that. So with that toolkit in its belt, it adjusted it to live in the water. It lost its legs, but it kept the musculature and therefore has a movement more like a dog in a shark-like body. That similar fusiform (rocket-shaped) body is required for fast swimmers in water. It even evolved a cartilaginous dorsal fin for stability, and its front fins are mostly immobile, but have the same bone structure as most mammals. That’s convergent evolution again.

Here’s a dolphin showing atavism, a recurrence of a trait or traits from an ancestral organism. Most dolphins no longer have their hind limbs. However they still have the genes for them and occasionally this happens and hind limbs grow again.

And here is a picture of a dolphin skeleton at the Bamfield Marine Science Centre. I took this photo on a field trip. This shows how the fins are homologous to our hands with the one bone – two bone – many little bones – five digits body plan first observed in the Tiktaalik fossil. I guess it might be ironic that the “hand” structure that we see in a dolphin to demonstrate how it once was descended from a land mammal also shows it is descended from a 375 million year old fish. Note that this skeleton was from a washed-up dead specimen and prepared by students. Some of the “fingers” are missing and incomplete.


Potato Growing Update

Sorry all. I am very busy trying to finish the Yearbook and have neglected my classes. However, you guys are amazing! Mike and Ryley did incredible sourdoughs and Aiden just sent me the following pictures of the potato plants he is growing. I grew up on Prince Edward Island so know a good potato plant when I see one, and this is one to be proud of. Check out the most famous Canadian song featuring potatoes!


Some Sourdough News


Hi Everybody,

Sorry for my absence. Working on the Yearbook is eating up my time. Mike Aguilar sent me a time lapse video of his sourdough starter and I thought I would share it, particularly since I killed two so far. My first one died for some unknown reason and my second one went moldy due to an over-tightened cover.

And if you want to learn more about sourdough, CBC did an interview with a sourdough researcher.



Surface-Area-to-Volume Ratio and Animal Organ Systems

I will no longer provide notes on the different animal phyla. It is taking too much time to convert them into note form. I may provide my last semester notes, with all their typos and mistakes, but will  concentrate instead on the ideas that connect all this together.

This post helps to explain why life on Earth was microscopic for 3 billion years and how it was able to overcome the physical constraint that imposed the size limit on life. Read these notes first:

2 Surface Area

I saved you the trouble of doing the math, however, try to understand what the math means. As much as students, typically, do not like math, it is the language of patterns and understanding some math allows us to understand why some phenomenon occurs as it does, and allows us to extend the pattern and make predictions. In this case, it explains why sponges are the way they are and could not change in the last 600 million plus years and why the evolution of organ systems allows the largest animal ever to exist on Earth, the blue whale, to exist. Which leads us to the following:

3 Homeostasis

With these two notes as background, you will have a better understanding of why the animal phyla showcased in the Shape of Life series progress as they do. I recommend you watch, or re-watch, the rest of the series with these notes in mind. The order should be, after the sponges,









The next set of notes will highlight the crustaceans and insects, sister clades, meaning they share a common ancestor. They look extremely different simply because one evolved for water and the other evolved for land. Again, life is the way it is because of the planet we live on. Just as how the planet is now is because of the life that evolved on it. We do not live on the planet, we are part of the planet and it is part of us.

Weighted Mean and Trimmed Mean Worksheets for Workplace Math 10

Hi Everybody,

Here are the latest and last worksheets for the statistics part of the Statistics and Probability Unit. The next worksheets will be on probability. As always, the worksheets are numbered, so I encourage you to do them in numerical order. However, with weighted mean and trimmed mean, the order you do them in is not important.

Weighted means are used in determining marks, with parts of the course worth different percentages of the final grade. Trimmed means are used in all manner of places, including Olympic scoring of gymnastics, figure skating and diving, the judged events. They drop the highest and lowest marks given by the judges to try to prevent bias from playing a part in the scoring.

3 Weighted Means

4 Trimmed Means

If you have questions, email me and I will help.

Worksheets for Workplace Math 10

Hello Workplace 10 Mathematicians. I have my edublog up and running, as you can see. For this post I am linking all the worksheets so far. Remember, do them in order. Most mathematics is linear, that is, the skills build upon previous skills. That’s why, if you missed something in a previous grade in math, you may find later concepts difficult to understand. Don’t jump ahead in math until you are ready.

For the mode, median, mean worksheet, I recommended to some students to skip the first problem if they didn’t master the skill of calculating weekly earnings. I modified that worksheet by showing steps  to guide you through solving practice #2. Use the same steps for practice #3 and the test question. When you complete the test question, take a picture of it and email it to me. If it is correct, I will mark it done and send you the next worksheet. If it isn’t, I will show you where your mistake(s) occurred and probably ask you to redo it. Or, I may send you another set of practice problems with another test question.

Remember, don’t jump ahead until you know you are doing the work correctly.

Here are the worksheets, most recent at the top, like these posts.

3 Weighted Means

2b Guided solution for #2

2 Practicing Mode, Median and Mean

1 Measures of Central Tendency

There will be a new worksheet soon.


Kingdom Animalia 3 – The Ediacarans

Hello, Life Scientists!

It’s been a busy time, but I am back! I have a new lesson. Rather than post/send the blank lesson and the class notes, which were huge files, I have typed out the notes and am sending them. It will simplify the process, I believe, although it is one of the reasons for the lack of speed in our progress. Typing is a lot slower than posting something I already wrote. However, the end product is better.

We watched a David Attenborough documentary before March Break called First Life about the Ediacara Period. The notes summarize the video. If you missed it or would like to review it, it is on YouTube at:


If you are living with any other science geeks, invite them to watch. And as you may remember, Mistaken Point, Nfld. features prominently in it.

Here are the notes for the ediacaran animals:

3 The Ediacarans (typed)

And for those who are missing the microbiology organisms, here is how you can enjoy them again and participate in one of the latest COVID-19 rages, sourdough bread. Courtesy of Sam Wong of New Scientist, here is how you can grow your own starter and make sourdough bread. My own starter, that I call Sam, is in the 3rd day of the process to make some bread.

How to make a sourdough starter and delicious sourdough bread _ New Scientist

If you want a bit more about sourdough bread, check out my Science for Citizens 11 post on the same subject.

Hello Life Sciences 11 students! I have my edublog going again. I’ve used it for years as simply a place to store the video links I use in class. Some of the links are dead. Not too surprising, I am the oldest male teacher in the school. I have links older than you are.

I sent out the first lesson last week and you haven’t heard anything since. More is coming. I am reading a fascinating book called The Strange Order of Things:Life, Feeling and the Making of Cultures by Antonio Damasio, a renowned neurologist that has me thinking differently about our next big topic, homeostasis and body systems. You will get the lesson soon.

But for now, here are the links to the pdf notes I sent you in case anyone accidentally deleted them.

1 Animal Cladogram

2 Phylum Porifera (with notes)

2 Phylum Porifera

And if you lost the link to the Shape of Life video on sponges and how to learn to visualize bird songs from the Cornell Ornithology Lab, it is here:

Plan for Life Sciences at Home

Activity 2 Growing Potatoes like a Martian

Hello again, Citizen Scientists! Our first activity was growing bacteria and yeast to grow starter so we can eventually use it to make bread. I’m calling my starter Sam after Sam McGee from Robert Service’s poem, The Cremation of Sam McGee.

I worked for a time in the Yukon for United Keno Mines in Elsa. I was there long enough to see the Yukon River freeze and thaw. That was the criterion to be called a sourdough. They were called sourdoughs because that’s what they smelled like.

Sourdough was a perfect food for the gold rush. Once you got it going, you didn’t have to buy yeast. You just used some of your sourdough. But it had to be kept warm. In the Yukon that can be difficult. I remember a stretch of -40 C weather. We weren’t allowed to work outside because you could freeze your lungs the air was so cold. It warmed up to -20 C and we all took off a layer of clothing.

The miners in the gold rush did the sensible thing. They wrapped their sourdough in cloth and kept it next to their skin, keeping their starter warm. Of course, many sourdoughs named their “pets,” after all, they had to continuously feed them and look after them. But if you keep a bunch of sourdough in your shirt, you are going to smell, shall we say, a bit funky. Hence the name sourdough.

This week we are going for a more modern tale, The Martian, starring Matt Dillon. In it, Matt Dillon’s character gets left on Mars and must wait months to be rescued. One of the issues is food and he famously grows potatoes using Martian soil and his feces. So, this week we are going to grow potatoes, without using our feces, please. The directions are below. Along with some interesting information about potatoes. You know, I’m from P.E.I. and I know a Russet Burbank from a Yukon Gold.

Week 2 Growing Potatoes Like a Martian