I'm an up-and-coming invertebrate zoologist interested in functional morphology,  invertebrate health, evolution, subtidal ecology, and behavior. I like to investigate how specific groups of organisms interact with their environment under changing conditions, like oxygen concentration, temperature, pH, ( etc.) starting at the organismal level.  Additionally, I am interested in developing health standards for different groups of invertebrates.

 

I am an MSc graduated from the lab of Dr. Richard Emlet at the Oregon Institute of Marine Biology (OIMB), University of Oregon. I currently work at the Charleston Marine Life Center as a Marine Science Educator, and aquarist. My research focuses on describing some characteristics, functional morphology and behavior of the basket star, Gorgonocephalus eucnemis, and the Western spiny brittle star, Ophiothrix spiculata.  I have also conducted complementary research in Panama on the sponge-dwelling brittle star, Ophiothrix suensonii.

 

Ophiuroids (my favorite group of organisms) are often overlooked in ecological studies, even though they can be found in every ocean basin from the tropics to the poles, and play important roles in their ecosystems. Fragile, yet resilient, I find them beautiful and intriguing.  The homepage background image is of one of my basket stars,  Gorgonocephalus eucnemis, perched atop a scarlet gorgonian.

Current Research
Solaster cf. paxillatus

Starting in 2021 I will be changing course a bit and will dive into the world of microbiology, epidemiology, aquatic invertebrate medicine, and pathology examining Sea Star Wasting Disease (now Asteroid Idiopathic Wasting Syndrome, AIWS). I will be starting a  P.h.D. program investigating the pathogenic analysis and treatment options for the wasting sunflower star, Pycnopodia helianthoides.

Stay Tuned. 

Left: Solaster cf. paxillatus

Recent Research
RSGPC gorgo prep.JPG

blue arrow- center of disc

aa- articulating area; abdm- abductor muscle attachment site; addm- adductor muscle attachment site; aoa- ambital ossicle attachment site; de- dermis; gp- genital plate; gpc- genital plate condyle;  ivm- intervertebral muscle; mr- radial shield mid-rib;  p- radial shield CaCO3 plates; rs- radial shield; rsdp- radial shield distal process; vao- vertebral arm ossicles

Respiration and the structures responsible for bursal ventilation in Gorgonocephalus

Gorgonocephalid disc-movement was first noted by Lymann (1882) while aboard the H.M.S. Challenger. This particular movement was disregarded as yet another feature indistinct from other ophiurans (although not all ophiurans exhibit this behavior). Over the years a few invertebrate zoologists speculated that this disc-pumping behavior ventilates the bursae and could possibly serve as a respiratory function. However, these speculations were left untested or investigated. 

 

In this study, I investigate if bursal ventilation in Gorgonocephalus eucnemis serves as a means of respiration, especially under changing environmental conditions such as (1) exposure to an increase in food abundance, and (2) decreasing environmental oxygen. In addition, I illustrate, confirm, and describe the anatomy responsible for creating the disc-pumping (bursal ventilation) movement.

 

These series of experiments constitute 2 of the 3 chapters of my Master's thesis and were presented at the 2018 WSN meeting.

SEM gorgo RSGP figure.JPG
Figure 9.jpg
Ch2 Fig 2.jpg

Ventilation rates through time for two specimens in the feeding study (A) and two specimens in the hypoxia study (B).   A. Black bracket denotes time period where specimens were actively feeding. Specimen #1 (black) and specimen #5 (grey), oxygen concentration (dashed black line).   B. Grey dashed line)- the start of nitrogen gas flow, (Grey dotted line) – nitrogen gas off, surface covered with plastic, (Black dotted line) – air pumps turned on, (Black dashed line)- O2 levels match beginning normoxic conditions Specimen #1(black) is different from the individual in A, and specimen #2 (grey).

Respiration and the structures responsible for bursal ventilation in  two Ophiothricids
CH2 Fig 5.JPG

The only previous attempt to test whether bursal ventilation was involved with respiration came from William Austin's 1966 dissertation. He briefly observed Ophiothrix spiculata under normoxic and hypoxic conditions, noting no significant change in rate of bursal ventilation. 
 

In this study, I re-evaluate the aforementioned, previous work with O. spiculata and another, similar-sized ophiothricid.  At STRI (Bocas del Toro, Panama) I investigate whether bursal ventilation serves as a means of respiration in Ophiothrix suensonii.   I illustrate, describe and create 3-D models of the anatomical features responsible for the observed bursal ventilation in both species.

 

I presented the work done on O. suensonii at the 2017 WSN meeting

(see poster link below) 

 

Ch2 Fig 9.JPG
CH2 Fig6.JPG

Images taken with a scanning electron microscope (and my illustrations below) detailing the similarities and differences between the radial shields and genital plates of Ophiothrix suensonii (A – C), and O. spiculata (D – E). A. Ventral view of radial shield, proximal tip broken. (abdm)- abductor muscle attachment sites, (addm)- adductor muscle attachment sites (aoa)- ambital ossicle/ abradial genital plate attachment site, (gp)- genital plate, (rs)- radial shield, dotted lines – edge of disc, (1-4) – genital plate condyle processes (see text).  B. Dorsal view of radial shield. C. Genital plate, interradial side. D. Ventral view of radial shield. E. Dorsal view of radial shield. F. Genital plate, interradial side.

Arrows point to some visible growth rings

Ageing Gorgonocephalus

Many slow-growing, long-lived echinoderms (like the red urchin, Mesocentrotus franciscanus)  can live to be 100+ years. Gorgonocephalus eucnemis, is also a relatively large, slow-growing echinoderm yet we do not have a clear age-range for this species. 

 

In this (ongoing) study, I attempt to age some G. eucnemis specimens by examining the growth rings present on their vertebral arm ossicles. 

Basket stars - Gorgonocephalus eucnemis.
food stealing.jpg
Intergenerational Kleptoparasitism?

While observing basket stars in my test aquarium, I observed an amazing behavior. I watched a juvenile basket star (which was strapped across the disc of an adult) reach into the adult's mouth, remove food items and subsequently place the items in its own mouth. After two years of collecting these animals for the experiments mentioned above, I have recorded this behavior in five separate pairs and have found specimens preserved in the act of stealing food. 

Link to pdf of CV
Research Gate
Pycnopodia larva, by R.B. Emlet
The emlet lab

Dr. Richard B. Emlet: MSc Advisor

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