This past weekend I was in the San Joaquin Valley to celebrate my dad's 80th birthday. On a cold and rainy Saturday morning we gathered at my parents' house to take care of some last-minute things before the big party later that evening. We were in the backyard when I noticed a tiny lizard on the patio under a table. It was so still even as I approached that at first I thought it was dead, but when I touched it it turned its head away from my finger and twitched a leg. Amidst suggestions of "Pick it up" and "Don't squish it!" I coaxed the little guy onto my hand and held it out for pictures, hoping I'd have time to ID it after all the birthday festivities.
Cute little thing, isn't it? The entire body is only about 5 cm long. It didn't look like any of the native lizards or salamanders that I've seen, and a little research on the excellent website California Herps confirmed that it is indeed an alien species.
Hemidactylus turcicus, the Mediterranean house gecko, has been living in California since at least as early as 2007. It is a nocturnal gecko that is usually associated with human dwellings, as artificial lights attract the moths and other insects that the gecko preys upon. The predatory habits of this H. turcicus make it a welcome, if informal, house pet in its native range. I was unable to find how H. turcicus made it into California from the Mediterranean, but I bet the original "colonists" were escaped pets. Since they are small (no longer than 15 cm) and nocturnal, they are not considered to be a threat to native California lizards, although their distribution in California seems to expanding northward.
Like most other geckos, H. turcicus has vertical pupils and doesn't have eyelids. In this picture you can see the pupil. We watched our little guy lick its eyeballs several times, which is what geckos do to keep their eyes clean and moistened.
There's no way of knowing how long this little gecko has lived in my parents' backyard, or now long it will live after I let it go. Now that I know about them, I'm going to keep an eye out for them around here where I live. According to the California Herps species map for H. turcicus, there has been at least one verified sighting in Santa Cruz County. They don't seem to be particularly shy, but their nocturnal behavior and small size may make them difficult to see even if they are fairly abundant. If one makes it into my house, I'll welcome it and hope my cats don't catch it. I wouldn't mind another mouth in the house, if it's one that I don't have to feed.
Last night the moon was new, meaning that we are now in spring tides. The spring tides occur during the new and full phases of the moon and result in the largest swings between high and low tides; in the weeks between the full and new moons we have neap tides, during which the height difference between high and low tide is smaller. As an intertidal biologist I look forward to and make use of the spring low tides, and after a year of pretty intensive field work I can feel in my body when they should be coming around. I love being that tuned in to the rhythm of the tides.
Yesterday a very large northwest swell came through the region, combining with the late morning high tide to generate some awesome (in the literal sense of the word) waves. For example, huge waves broke over the pier in Ventura, causing officials to close the pier until further notice. Alas, I was in class all morning and didn't get out to the marine lab until early afternoon, at which time the tide had receded (yesterday's low was at 16:48) so I didn't get to catch any of the action.
Made up for it today, though. Knowing that high tide would be at about 10:00 I made sure to be out at the lab for my daily chores after breakfast. Patience was rewarded!
Here's the view from the cliff at Terrace Point:
The waves were at least twice as tall as I am. I could feel them crash into the cliff beneath my feet. There's nothing quite like being reminded that Mother Nature has home field advantage. Here's the action looking east towards Natural Bridges and Santa Cruz. Hard to believe that I spend hours crawling around on those benches, isn't it?
Out at Terrace Point there's a non-public-accessible platform that lab staff have access to for water sampling. Every day, conditions permitting, a technician goes down the steps and throws a bucket off the cliff to grab a water sample and take the temperature; it's a fun task that I've done a bunch of times. I don't think the outside water temperature is going to be taken today. Take a look at this sequence of photos, taken in a 5-second time span, and imagine yourself standing on that platform. Yeah, you don't want to be there.
The biggest splashes occur when a wave is reflected off the cliff and crashes back into a second oncoming wave. To see this I walked over to a different area of the lab and looked down onto Younger Lagoon. There's a rock island in the mouth of the lagoon that almost always has birds perched on it. Sometimes the birds are pelicans or pigeons. Today they were cormorants and gulls.
The west-facing cliff of Younger Lagoon is perfectly situated to reflect back these northwest swells. Watch for yourself:
Watching this reminded me of a passage from Sebastian Junger's The Perfect Storm, in which he describes the waves that ultimately sank the fishing boat Andrea Gail in the North Atlantic. It's a visceral demonstration of the ocean's power. All of a sudden the adage "Never turn your back to the ocean" seems rather trite, doesn't it?
My most recent batch of sea urchin larvae continues to do well, having gotten through the dreaded Day 24. I haven't written about them lately because they're not doing very differently from the group that I followed last winter/spring. However, I've been taking photos of the larvae twice a week and it seems a shame to let them go to waste, so I've put together a progression of larval development. As a reminder, the last time I wrote about these larvae they were six days old.
Age 9 days: The larvae had four arms and were growing their skeletal arm rods. Their stomachs, which we keep an eye on because their size can tell us whether or not we're feeding them enough, were a bit small but not so much so that I worried.
Age 12 days: The larvae were growing their third pair of arms. Some had just begun growing the fourth pair of arms. Red pigment spots also start appearing all over the body. Some larvae develop lots of red spots, others have very few. Notice that the stomach is slightly pear-shaped; this is normal.
Age 17 days: This larva doesn't look appreciably different from the previous one. This photograph, though, is a bit clearer. The stomach has taken on a pink tinge, due to the red color of the food the animal is eating, and the mouth is the large rounded triangular in the in-focus plane. The pair of skeletal arm rods that are in focus are protruding from the ends of the arms, which raises is something to be concerned about. Sometimes the first sign of imminent doom is the shriveling of the arms, so seeing the rods sticking out makes me think "Uh-oh. . ."
Age 24 days: This is about the time in larval development when things often start to go wonky. I've looked back at my notes from previous spawnings of S. purpuratus, and seven of the 20 cultures that crashed did so in the week between days 20-28 of development. Some of these cultures were doing well right up to the point that they all died. They were literally there one day and gone the next.
Nonetheless, the current batch of larvae continued to do well. The fourth pair of arms were slow to grow but otherwise the larvae look fine. The top larva in the picture below is lying on its back, so you are looking onto the ventral surface. On the left side of the stomach there's a little upward-facing invagination; this is part of the initial water vascular system forming. Note also that the overall shape of the larvae is changing a bit. They are becoming less pointy and a bit rounder.
Age 30 days: At this stage the juvenile rudiment is clearly visible. You can see it as a rather nondescript blob of stuff to the left of the gut. The fourth pair of arms have also grown quite a bit but are still considerably shorter than the others. This individual has two bands of cilia, called epaulettes, that encircle the body. These epaulettes will become more conspicuous as the larva approaches competency.
Age 33 days: Today I got lucky! The larvae looked good when I changed their water this morning <knock on wood> and although I'm keeping my fingers crossed I have high hopes for these guys. They're about as big as they're going to get, measuring 760-800 µm in length. They will get heavier and more opaque as the juvenile rudiment continues to develop.
The really cool thing is that one of the larvae landed on the slide exactly as I wanted it to. It happened to fall onto its left side and stayed there, so I was able to focus up and down through the body to get the rudiment into focus.
Do you see five small roundish blobs that are evenly spaced around the larger golden circular blob? The large blob is the stomach, seen in side view. Those smaller blobs are tube feet! Don't believe me? Then take a look at this close-up:
Now if those don't look like tube feet, then I'll eat my hat. What's also noteworthy about this larva is that its epaulette bands are both visible, especially the posterior-most one.
So far, so good. I won't know how successful larval development is for these guys until they either make it through metamorphosis, or not. In a very real sense, I won't be able to draw any conclusions about the success of larval development until they either become established as juvenile urchins, or not. One of my graduate advisors inherited a couple of sayings that he passed on to me, as well as to a whole generation of aspiring invertebrate zoologists:
The animal is always right.
The life cycle is the organism.
The first is a given, right? The animal knows what it is and what it's doing, even if we humans have no clue about what's going on and can't decide what its name should be.
The second saying might be a little less intuitive. What it means is that, for organisms with a multi-stage life cycle, you have to consider all of the stages if you want to understand them. This is a much more holistic view of biology, and it's the one that appeals most strongly to me. When I'm thinking as a naturalist, I find my thought process constantly switching between "forest" and "trees" as I seek to understand even a teensy bit of the world around me. While it's easy to get distracted by all the cool details of organisms, it's important to step back and ask myself, "What does it all mean? What is the big picture here?" So yeah. Perhaps when (if!) these larvae turn into urchins and I've got them feeding on macroalgae in a few months, I'll be able to say whether or not larval development was successful. If all goes well this larval phase, as all-consuming and fascinating as it is to me, will be only a small part of these animals' lives.
This morning I was teaching lab when three of my students in the back corner called me over to where they were working. "We have a problem," one of them declared.
Since they were making posters I assumed that the problem had to do with format or content or something related to the scientific papers they were analyzing. When I got back to them and asked what the problem was, they just pointed at the corner of one of the counters. "You've almost put your hand on it," one of them said.
I looked under my hand . . . nothing. "No," the student continued, "it's under the edge."
I looked under the lip of the counter and there was a tiny spider just starting to lower itself on an invisible strand of silk. And I do mean tiny: the entire body would have fit onto my thumbnail, with room to spare. Seeing that it was a jumping spider and nothing to be afraid of, I captured it in my hands and released it outdoors. Meanwhile, the students cowered and kept their distance.
Here's the only picture I was able to take before returning to the classroom. I was supposed to be teaching, after all.
Intrigued as I usually am by something I don't know much about, I looked up California jumping spiders after class. I knew it was a jumping spider because I've seen many of them before, and they really can jump. This little one, measuring maybe 1 cm in total length, jumped about 10 cm when I put it on the railing outside. Then it scurried to the edge of the railing and went overboard. Jumping spiders are super cute. If you don't believe me, ask the almighty Google to show you some mating dances of male jumping spiders. I dare you not to be impressed.
Jumping spiders belong to the appropriately named family Salticidae. They are little spiders, rather hairy, with shiny black eyes. Because of their small size they often don't provoke the knee-jerk "KILL IT!" response except from true arachnophobes. The one my students found today is, I think, a female red-backed jumping spider (Phidippus johnsoni). Both sexes in this species have a red abdomen; in males it is solid, while the females have a black stripe running down the center.
All spiders are hunters, capturing prey by various means and killing it with a venomous bite before slurping up the juicy insides. A little jumping spider could bite a human, but I've handled many of them and have never been bitten. The trick, I think, is not to make the animal feel threatened. If it perceives your hand as just another surface to crawl on, it won't waste its venom on you. Not that I would try this with a spider known to have a bite that is dangerous to humans, mind you. Jumping spiders often end up inside houses, though, and it's good to know that you can gently pick them up and put them outdoors where they will be happier. You might also be happier, knowing that the spider isn't inside with you!