Cephalothrix species we find as orphan larvae in the plankton. Scale bars 100 µm.
Generalized Cephalothrix larva with paired intra-epidermal eyes and lateral cirri.
Cephalothrix spp.
Two species in the genus Cephalothrix (=Procephalothrix) are reported in the NE Pacific (Roe et al. 2007): C. spirals and C. major. However, we find that there are likely at least six species in Southern Oregon alone and four of those we have collected as larvae only. Larvae of the genus Cephalothrix have paired intra-epidermal eyes. In some species each eye consists of two small eyes (e.g., Cephalothrix sp. 1, Cephalothrix sp. 2). Cephalothrix larvae often have a small apical tuft, posterior cirrus, and lateral cirri. In our experience, the lateral cirri are symmetrical and are usually anterior to the eyes.
Oocytes and sperm of Cephalothrix spiralis dissected from ripe adults in March 2013. Larvae of artificially reared C. spiralis at four and 11 days (left to right). Scale bars 100 µm.
Months collected: Feb–March
Cephalothrix spiralis
Sequence Data: 16S, COI
We have collected the adults of C. spiralis on multiple occasions on the southern Oregon coast and were able to rear larvae from adults in March 2013. Eggs are 95 µm in diameter, have an egg jelly layer, and sperm headpiece is approximately 2–4 µm in length. Brownish orange epidermal granules are apparent in young larvae, and a prominent apical tuft is visible at four days after fertilization. The larvae have eyes as well as several (relatively) long lateral cirri by 11 days and some individuals had thick anterior comb-like cirri. Unfortunately, we are yet to identify the preferred food for Cephalothrix larvae and we were not able to rear these larvae beyond 18 days.
Larva of Cephalothrix sp. 2 collected from the plankton January 2013. Pairs of intra-epidermal eyes are sometimes so close together, they appear as one (compare left to right). Note large mouth opening at 8 o'clock (right). Scale bar 100 µm.
Cephalothrix sp. 2
Sequence Data: 16S, COI
Observed in Coos Bay: Jan, Aug, Oct
This is an example of a Cephalothrix species that we currently only find as larvae in the plankton. This species is recognizable by two double eyes and lateral cirri as in other Cephalothrix larvae, but individuals also have a dark grapefruit pink body and gut color. A young individual, collected in August (right), had long lateral cirri, but another larger individual that we collected in October had truncated cirri (above).
Cephalothrix sp. 1 larva collected November 2013, note epidermal yellow pigment (the species name-sake) and lateral cirrus anterior to the left eyes. Scale bar 100 µm.
Cephalothrix sp. 1
Sequence Data: 16S, COI
Observed in Coos Bay: Jan, Feb, May, July, Sep-Nov
Larvae of this species are common in Coos Bay plankton. We find individuals almost year-round, with most collected in May. We have yet to find the adults of this species but their larvae are easy to recognize by their yellow epidermal granules. They also have two double eyes. In young individuals, the eyes are not always doubled. Near the eyes are lateral cirri that are not excessively stiff (as in Tubulanus larvae), but do not flap (as in Carinoma larvae (e.g., Carinoma mutabilis)). The larvae are often quite large (500–750 µm), have a large mouth, and we have observed planktonic individuals with a very well developed proboscis.
Cephalothrix sp. 2 larva collected October 2013, note right lateral cirrus (left), and two paired eyes that look single (middle) but are each doubled (right). Scale bars 100 µm.
The larva of Cephalothrix sp. 3 was collected in May 2013 and had blue pigment, red anterior and pale ventral pigment patches (middle) near the mouth (pale circle, right). Scale bars 100 µm.
Cephalothrix sp. 3
Sequence Data: 16S, COI
Observed in Coos Bay: May
We only observed this larva once. It is bright blue and easy to spot in plankton samples. Upon closer inspection, it has reddish pigment between the blue and pale regions ventrally near the mouth. This individual had two eyes which were intra-epidermal, but not doubled. Additionally, there was a general reddish hue anteriorly. We also did not notice any distinct lateral cirri and the mouth was small, unlike in other Cephalothrix larvae. This larva represents yet another undescribed species for which we have yet to find adults.
The larva of Cephalothrix sp. 4 collected February 2013, note two single eyes and one lateral cirrus in focus and below left eye. Scale bar 100 µm.
Cephalothrix sp. 4
Sequence Data: 16S, COI
Months collected: Feb, March
We’ve found these Cephalothrix larvae several times since 2009, usually in early spring. They are characterized by paired single eyes (rather than paired double eyes found in other local Cephalothrix larvae), a large slit-like mouth and lateral cirri. They also tend to have orange or brownish epidermal color and lipid droplets within the gut, but these characters are less consistent than others (e.g., single eyes).