Nanomia bijuga
Common Names: Siphonophore
Scientific Name: Nanomia bijuga
Size Range: Up to 30cm in total length
Nanomia bijuga belongs to the order Physonecta within the subclass Siphonophorae within the class Hydrozoa.
It is a predator that represents a colony of many genetically identical individuals called zooids that make up the whole. It has a pigmented gas filled float called a pneumatophore at its tip.
Please come back – more information will be posted soon on this fascinating siphonophore!
Photos by D. Young
Nanomia bijuga collected in Cadboro Bay, Victoria, British Columbia. This is the position they are normally found in when at rest in the water, however, they can swim quite fast and may be close to horizontal at these times.
Ctenophore (comb jellyfish) Larva – Cyddipid Larva February 19, 2013 Plankton Tow – Cadboro Bay Unidentified Larva – Likely a Cydippid (ctenophore) Larva Author: Allie and Judah
Barnacle Larva – Nauplius Larva February 19, 2013 Plankton Tow – Cadboro BayAuthor: Alondra
The nauplius larva is the first swimming larval stage of a barnacle. After this stage it changes into a cyprid larval stage and then anchors itself onto a substrate as an adult barnacle.
Sea Gooseberry from Plankton Tow Author: Cara Mackenzie Common Names: Sea Gooseberry Scientific name: Pleurobrachia bachei
This is likely the zoea of a Dungeness Crab Author: Rachel Walker Illustration by Spencer Sivertson
Beroid Comb Jelly (Beroe abyssicola)
Author: Adam Kitzler
Common name: Beroid Comb Jelly
Scientific name: Beroe abyssicola
Size range: up to 7 centimetres
Identifying features
Beroe abyssicola has a cylindrical shape with rounded ends, they bear eight evenly spaced rows of cilia or “combs” which they beat in waves for locomotion. the comb rows stop just before the oral end where a mouth, resembling a pair of lips, is located. Their most distinguishing characteristics are their translucent, pinkish red colouration through which their more intensely coloured pharynx is visible, as well as their complete lack of tentacles.
Habitat
They inhabit the waters of the North Pacific at an average depth of 1028-1840 metres. They will occasionally come to the surface, however they may lose their pinkish colouring in the process.
Prey
Beroe abyssicola is a carnivorous predator that swims, hunting for prey, with its mouth closed for a more streamlined shape. when it encounters prey, of which it prefers other ctenophores, it can open its mouth to quickly engulf its prey. It can even swallow other ctenophores larger than itself, or bite pieces off with its fused cilia, called macrocilia that line the inside of its mouth and function as simple teeth.
Predators
Not much is known about what exactly preys upon Beroe abyssicola, but the most likely predators are other ctenophores, jellyfish and other animals like fish and sea turtles.
Life cycle
Beroe abyssicola is a hermaphroditic species, meaning that it has both female and male gonads. As a result it is thought to be able to occasionally fertilize its own eggs. Regardless it will eject its sperm and/or eggs directly from the mouth into the open water where the eggs are fertilized externally. After fertilization the eggs will go through a larval stage, resembling a smaller adult, that will grow into a full adult. Throughout the life cycle it will remain part of the phytoplankton and is therefore considered holoplanktonic.
Behavior
Beroe abyssicola does not have a very complex nervous system; it has a loose net of nerves spanning its body called a nerve net that may be more concentrated near sensory organs. Because of its simple nerve network it is limited to simple behaviors, such as swimming and navigating for prey, maneuvering away from obstacles and feeding on located prey, which it is able to sense with chemo receptors.
Photographs and Video by Adam Kitzler and D. Young
Barnacle Larva – Cyprid Larva February 19, 2013 Plankton Tow – Cadboro bay, Victoria BC Author: Judah
This is the last planktonic larval stage of a barnacle before it becomes permanently anchored as an adult to a substrate.
Sea Gooseberry
Author: Max Newell and Marlo Osborne-Subasic
Common name: Sea Gooseberry
Scientific name: Pleurobrachia bachei
Size range: Up to 15 mm
Identifying Features
Pleurobrachia bachei are the most common comb jelly in the Victoria region. They are transparent and nearly spherical. Extending across the entire circumference you will find eight comb-rows evenly spaced. Comb-rows are made up of rows of comb-like cilia which are used for locomotion; they also refract light in a way that causes the gooseberry to shimmer with multiple colours all over its body. This species has two long tentacles (around 14cm in length) that come out from short tentacle bulbs that are pressed up against each side of the pharynx. These tentacles have smaller tentillum coming off of them which makes them resemble a feather when they are fully extended. When P. bachei is hunting the long tentacles are extended and dragged behind but they can be fully retracted into the tentacle bulbs if it is disturbed. They are made up of 99% water and, similar to other gooseberries, are biradially symmetrical. They can be found in large swarms particularly during warm summer months in sheltered bays.
Habitat
Pleurobrachia bachei have been seen as far north as Alaska and as far south as Acapulco, Mexico. Sea Gooseberries are pelagic and are frequently found in water close to shores. Different species can be found all over the world and may occur in shallow waters as well as in deep oceans. During the summer months along the west coast of North America P. bacheican be found in large swams and some individuals can become trapped within rock pools when the tide is falling.
Life Cycle
All gooseberries are hermaphrodites and reproduce sexually. Fertilization takes place externally and the resulting larvae (known as cydippid larva) are free swimming. Most gooseberries die after spawning. The Sea Gooseberry is planktonic its entire life, and there is no sessile stage. Once a larva has become a fully grown gooseberry, it is capable of releasing up to 1000 eggs per day. Gametes are released into the ocean via the gonopores, located on the comb-rows. The average lifespan of the Sea Gooseberry is 4.6 Months (140.01 days).
Food (Prey)
P. bachei hunt by extending their two long tentacles behind them and swimming through the water column. As the tentacles touch their prey, they become stuck to the specialized sticky cells on the tentacles called “colloblasts”. Once the prey is stuck, the gooseberry spins to wrap its tentacles around itself so that it can take the food trapped in its tentacles into its mouth. The P. bachei kept in our school aquarium feed upon newly hatched live brine shrimp (Artemia sp.). Unlike P. bachei, other gooseberry species such as the Beroid Gooseberry (Beroe abbysicola) are aggressive ambush predators that hunt without using tentacles. They primarily eat copepods and krill, but also eat fish eggs, mollusks, small crustaceans, larvae, and even other gooseberries.
Predators
The P. bachei is often preyed upon by large jellyfish such as Aurelia aurita and A. labiata. It is also eaten by fish like salmon and sometimes sea turtles. They can only escape from predators by beating the cilia in their comb-rows, and are the largest animals in the world to move through the use of cilia.
Video 1 by D. Young
Video 2 “Sea Gooseberry – close up” by Saidi, Hanna and Marijke
photos by D. Young and Cara Mackenzie