VCP: Introduction

Very Basic Copepod Introduction

(Skip this if you already know what a copepod is.)

Copepods are a type of crustacean, the class of animals that also includes shrimps, lobsters, and crabs. Copepods are one of the most abundant animals on the planet. Most are saltwater plankton, living their entire lives in the open ocean without ever touching the bottom or surface. Copepods also live on the sea bottom, in fresh water, as parasites on fish, in caves...

Euchaeta Biological Introduction

Euchaeta are gigantic (for copepods), with the adult subtropical females growing to 2.4 millimeters in length and the polar species reaching up to 1 cm. Males are somewhat smaller. Their maxillipeds are used to capture and eat other copepods. These photos depict the structure of the capture appendages, the maxillipeds and maxillae. The left photo is a drawing from Wickstead(1959). The right is a scanning electron micrograph by J. Yen(1985).

Computer Visualization Introduction

We created and animated our model using 3D Studio Max from Discrete Logic. This high-end animation package is widely used by movie special effects artists.

To create our models and animations, we first looked at illustrations in the literature. Rose 1933 gave us a good starting point. To create the prosome, we scanned 2D images from Rose into the computer and traced them using Bezier curves to create the outline of the prosome as seen from the left-hand side. We then made an estimate of curves representing the outline of the prosome as seen from the rear. Using these two sets of curves, we were able to create a Bezier patch surface approximating the prosome. We then checked our results by rendering images from several viewpoints and comparing them against preserved specimens. We also showed the images to Annie Townsend, curator of the SIO Planktonic Invertebrates Collection. She was able to suggest many important improvements.

The other segments of the prosome and urosome were constructed in a similar fashion, as were the appendages. We found that NURBS surfaces generally gave better results with less effort than other techniques for modelling curved surfaces.

Setae provided a special animation challenge, as there are so many of them. After exploring several techniques we used loft surfaces created from circles and Bezier splines. The tip of each seta was attached to a controller, so that each seta could be individually positioned if necessary. We generally avoided this by attaching the tips of each set of setae to a master controller. To give a more natural appearance, the setae on the maxillae are translated and rotated using a random noise function.

To animate our model, we first determined the range of motion of the joints by examining preserved specimens. We then looked at video of live animals. Using key frame animation, we were able to approximate the motion of the living animals. Once the computer model had been animated, it could be examined from any angle and at any speed.

All images, animations, models, and scripts are copyright 2000 Scripps Institution of Oceanography and may not be published or re-used without permission.

VCP: Still Image Gallery

Bottom oblique view	Close-up view	Comparison Top
Head-on capture view	Left Comparison Image	Left view
Still top oblique view		Top oblique view close up

VCP: Animations & Movies

3D rendering of a copepod 1st antenna	3D Surface Rendition Images provided by Marie Bundy Animation created by Corey Accardo.
Tethered Capture	Here we see the carnivorous copepod, Euchaeta rimana (2.4 mm), restrained on a tether so that it remains within the field of view. A smaller copepod, Acartia (0.7 mm), makes contact with the predator but that does not trigger the attack response. When the prey escapes and sheds a wake toward the predator, then the predator reaches out with its maxillipeds and grabs the small copepod prey. The prey is then seen as a small morsel being shoved into the mandibles of the predatory copepod. (Videos done by J. Yen in collaboration with J.R. Strickler).
Tethered Escape Behavior	High-speed video (1000 fps) of the leg movements of Calanus pacificus. Note the sequence of coordinated movements of the 5 pairs of swimming legs. The name "swimming legs" is misleading as they are only used in the escape or lunge movements while the cephalic appendages are used in normal swimming.(Video recorded by S. Wilson)
Untethered Capture	This sequence shows how a freely swimming predatory copepod, Euchaeta rimana (2.4 mm, central image), lunges after another smaller copepod prey (Acartia, 0.7 mm, images to right of larger copepod). The Acartia was entrained in the feeding current of Euchaeta. When it detected the presence of the predator, it jumped away and shed a jet-like wake toward the predator. The predator sensed the strength and directionality of the prey's wake and lunged at it accurately to capture it in 3D space (capture occurred in upper right corner of frame; Doall et al. submitted). Lunge is much faster in relative speed than that of a running cheetah. (Videos done by J. Yen in collaboration with J.R. Strickler).
Untethered Escape Behavior	This sequence shows how a freely swimming predatory copepod, Euchaeta rimana (2.4 mm, central image), lunges after another smaller copepod prey (Acartia, 0.7 mm, images to right of larger copepod). The Acartia was entrained in the feeding current of Euchaeta. When it detected the presence of the predator, it jumped away and shed a jet-like wake toward the predator. The predator sensed the strength and directionality of the prey's wake and lunged at it accurately to capture it in 3D space (capture occurred in upper right corner of frame; Doall et al. submitted). Lunge is much faster in relative speed than that of a running cheetah. (Videos done by J. Yen in collaboration with J.R. Strickler).
Horizontal Spin	Computer-Generated Horizontal Spin Appendages in neutral position.
Fly-Around	Computer-Generated Fly-Around Appendages in neutral position.
Computer Visualization of Capture Behavior	Computer Visualization of Capture Behavior.
Computer Visualization of Capture Behavior	Computer Visualization of Capture Behavior
Computer Visualization of Capture of Prey	Computer Visualization of Capture of Prey
Computer Visualization of Capture of Prey 2	Computer Visualization of Capture of Prey 2
Computer Visualization of Escape Behavior	Computer Visualization of Escape Behavior: Note how the antennules oppose the motion of the tail, preventing the animal from moving backwards when the tail comes up.
Capture time sequence	This sequence of images shows the side view and head down view of the capture response of the subtropical carnivorous copepod, Euchaeta rimana (2.4 mm), as recorded using high-speed film (J. Yen, D.M. Fields, M.H. Doall in collaboration with J.S. Strickler). At 0 msec, the maxillepeds (mxp) are tucked in against the body (the arm-like appendage is the mxp in the upper frame and the straight appendages in the lower panel are the paired antennules extending to either side of the body). At 6 msec, the mxp begin to extend with its setae flared (upper panel) and the 'elbows' bowed out. The paired maxillae are also seen to participate in this capture response. At 8 msec, the mxp are fully extended with setae fully flared (upper panel), reaching out far from its body (lower panel). At 16 msec, the show is nearly over with the mxp withdrawing closer to the body (upper panel) and being tucked in among the other cephalic appendages (lower panel). (Slides prepared by R. Foster).
Capture time sequence 2	This sequence of images shows the side view and head down view of the capture response of the subtropical carnivorous copepod, Euchaeta rimana (2.4 mm), as recorded using high-speed film (J. Yen, D.M. Fields, M.H. Doall in collaboration with J.S. Strickler). At 0 msec, the maxillepeds (mxp) are tucked in against the body (the arm-like appendage is the mxp in the upper frame and the straight appendages in the lower panel are the paired antennules extending to either side of the body). At 6 msec, the mxp begin to extend with its setae flared (upper panel) and the 'elbows' bowed out. The paired maxillae are also seen to participate in this capture response. At 8 msec, the mxp are fully extended with setae fully flared (upper panel), reaching out far from its body (lower panel). At 16 msec, the show is nearly over with the mxp withdrawing closer to the body (upper panel) and being tucked in among the other cephalic appendages (lower panel). (Slides prepared by R. Foster).

VCP: Links

Copepods have a strong presence on the web. Here are some links:

• The Biology of Copepods at the University of Oldenburg
• Monoculus, the copepod newsletter (also at the University of Oldenburg)
• The World of Copepods at the Smithsonian
• Sean Avent's Copepod Page
• Copepods at Geocities
• Copepods Web Portal at the University of L'Aquila.

All images, animations, models, and scripts are copyright 2000 Scripps Institution of Oceanography and may not be published or re-used without permission.

VCP: Acknowledgements & Bibliography

Acknowledgements

We'd like to thank the following people for their help:

• J.C. Liu, S. Wilson, and R. Strickler for work on the live videos.
• D.M. Fields, M.H. Doall, and R. Foster for work on the capture sequence images.
• Stephanie Wilson for reviewing our animations.
• Annie Townsend, Curator of the SIO Planktonic Invertebrates Collection for helping us examine preserved specimens, for reviewing our models for correctness, and for providing us with many useful references.
• Alex De Robertis for help with copepod biology and for general advice and moral support.

Bibliography

In addition to our examination of preserved specimens, we obtained anatomical data from several sources including:

• Hardy, A. 1970. The Open Sea. The World of Plankton. 335 pp. Collins, London.
• Huys, R. and G.A. Boxshall. Copepod Evolution. 468 pp. The Ray Society, London.
• Mauchline, J. 1998. The Biology of Calanoid Copepods. Volume 33 of Advances in Marine Biology series. 710 pp. Academic Press, New York.
• Park, T. 1996. Taxonomy and Distribution of the Marine Calanoid Copepod Family Euchaetidae. Volume 29 of Bulletin of the Scripps Institution of Oceanography series. 203 pp. University of California Press, San Diego.
• Rose, M. 1933. Faune de France: Copepodes Pelagiques. 374 pp. Paul LeChevalier, Paris.
• Wickstead, J.H. 1959. A predatory copepod. J. Anim. Ecol. 28: 69-72.

Behavior data and other information for the project came from the following sources:

• Doall , Michael H.1995. The components of predation between Euchaeta rimana, a predatory calanoid.
• Fields, David. 1996. Interactions of marine copepods with a moving fluid environment. Ph.D. thesis.
• Hardy, A. 1970. The Open Sea. The World of Plankton. 335 pp. Collins, London.
• Liu, Jerry. 1996. Effects of morphology on the biomechanics of the high speed escape reaction of copepods: Developmental and species differences. M.S. thesis.
• Wickstead, J.H. 1959. A predatory copepod. J. Anim. Ecol. 28: 69-72.
• Yen, J. 2000. Life in transition: balancing inertial and viscous forces by planktonic copepods. Biol. Bull. 198: 213-224.
• Yen, J. l985. Selective predation by the carnivorous marine copepod Euchaeta elongata: Laboratory measurements of predation rates verified by field observations of temporal/spatial feeding patterns. Limnol. Oceanogr. 30:577-595.
• Yen, J. and J.R. Strickler. 1996. Advertisement and concealment in the plankton: What makes a copepod hydrodynamically conspicuous? Invert. Biol. 115: 191-205.

We used the following software packages:

• 3D Studio Max from Discrete Logic for 3D animation
• Adobe Premiere from Adobe Systems to create animations and for video editing
• Micrografx Picture Publisher from Micrografx to manipulate images for web publishing

All images, animations, models, and scripts are copyright 2000 Scripps Institution of Oceanography and may not be published or re-used without permission.